Motor housings

Abstract

An outer housing 200 for a motor 1, the outer housing receiving an inner housing 100 with a portion of the outer housing abutting a portion of the inner housing to form a fluid chamber 8 around the inner housing to receive a fluid for cooling the inner housing. The outer housing is structured so that any fluid leaking from within the inner housing is directed to an exterior 9 of the outer housing and thereby prevented from entering the fluid chamber. An inner housing retains within it a portion of a motor, e.g. stator 4, and defines a region 7 through which cooling fluid can flow to cool the motor. There may be a gap between the housings via which the leaking fluid is directed to the exterior. The outer housing may have vents 211a-b extending through the housing to connect an inner portion of the outer housing with an exterior of the outer housing, where the leaking fluid is directed to the exterior through the vents. The inner housing may have channels 112a-b to collect the leaking fluid.

Description

The present disclosure relates to an outer and inner housing, particularly to outer and inner housings for a motor. BACKGROUND In general, a motor housing may have the capacity to cool a number of components using a fluid for each component to be cooled. Cooling of motor components may help to regulate the motor temperature which in turn maximises the motor performance and efficiency. SUMMARY OF THE INVENTION Examples herein relate to an inner housing configured to house a portion of a motor, and to an outer housing that is configured to house the inner housing. The inner housing comprises a region through which cooling fluid can flow to cool part of a motor therein and the outer housing is configured such that when the inner housing is received in the outer housing a fluid chamber is formed around the inner housing to receive a fluid for cooling the inner housing. Thereby, fluid in the region defined by the inner housing cools the motor and fluid in the fluid chamber defined by the outer housing cools the inner housing (in turn this facilitates the cooling of the motor). Fluid in the region defined by the inner housing may be gas, such that the inner housing defines a gas chamber to receive gas to cool the motor therein. The fluid in the fluid chamber may be a liquid such that the fluid chamber is a liquid chamber and the inner housing is cooled by a liquid. Fabricating a motor housing using techniques such as sand casting may be able to achieve total isolation of the gas chamber and the liquid chamber described above however such methods are not cost effective when large quantities are required to be manufactured. Fabricating a motor housing using die casting methods may be cost effective for manufacturing large quantities but may not result in total isolation between the gas and liquid chambers due to the piece-wise nature of how components are formed as part of the die casting process. If any fluid leaking from one chamber were to enter the other chamber then cooling may not be as effective and other issues may arise. Nevertheless, many motor housings, even those employing seals, have a minimum leakage of a certain amount per year (e.g. 2 grams per year). Examples of this disclosure are directed to motor housing components that minimise any negative effects of such unavoidable leakage while being cost effective to manufacture in large quantities. According to an example of this disclosure there is provided an outer housing for a motor. The outer housing is configured to receive an inner housing such that a portion of the outer housing abuts a portion of the inner housing to form a fluid chamber around the inner housing to receive a fluid for cooling the inner housing. The outer housing is configured such that any fluid leaking from within the inner housing is prevented from entering the fluid chamber. Optionally, the outer housing is configured such that any fluid leaking from within the inner housing is directed to an exterior of the outer housing and thereby prevented from entering the fluid chamber. Optionally, the outer housing is further configured such that any fluid leaking from within the fluid chamber is directed to an exterior of the outer housing. The outer housing may be configured such that any fluid leaking from within the fluid chamber is directed to an exterior of the outer housing via a gap between the outer housing and the inner housing when the inner housing is received in the outer housing. The outer housing may comprise a vent extending through the housing to connect an inner, or interior, portion of the outer housing with an exterior of the outer housing. The outer housing may be configured such that any fluid leaking from within the inner housing (e.g. from an interior thereof) is directed outside the outer housing via the vent. The outer housing may be configured such that any fluid leaking from within the fluid chamber is directed to an exterior of the outer housing via the vent. The outer housing may comprise first and second vents, each vent extending through the housing to connect an inner portion of the outer housing with a region outside the outer housing, the outer housing being configured such that any fluid leaking from within the fluid chamber is vented outside the outer housing via the first vent, and any fluid leaking from within the inner housing is vented outside the outer housing via the second vent. The housing may comprise a plurality of vents. The plurality of vents may be spaced-apart in a circumferential direction of the outer housing. According to an example of this disclosure there is provided an inner housing for a motor. The inner housing is configured to retain a portion of a motor therein, the inner housing defining a region through which cooling fluid can flow to cool the motor therein, the inner housing configured to be received in an outer housing such that a portion of the inner housing abuts a portion of the outer housing to form a fluid chamber around the inner housing to cool an outside surface of the inner housing. The inner housing is configured such that any fluid leaking from within the inner housing is prevented from entering the fluid chamber. Optionally the inner housing is configured such that any fluid leaking from within the inner housing is directed to an exterior of the outer housing and thereby prevented from entering the fluid chamber. Optionally, any fluid leaking from within the inner housing is directed to an exterior of the outer housing and thereby prevented from entering the fluid chamber. The inner housing may comprise a channel configured to collect any fluid leaking from within the inner housing. The inner housing may comprise a channel configured to collect any fluid leaking from the fluid chamber. The channel may extend in a circumferential direction of the inner housing. The inner housing may comprise a first flange configured to direct any fluid leaking from within the inner housing to a region external to the outer housing when the inner housing is received in the outer housing. The inner housing may comprise a second flange configured to direct any fluid leaking from within the fluid chamber to a region external to the outer housing when the inner housing is received in the outer housing. The first and second flanges may be the same. According to an example of this disclosure there is provided a motor unit comprising an outer housing as described above and an inner housing as described above, the inner housing being received in the outer housing such that the fluid chamber is formed around the inner housing to receive the fluid for cooling the inner housing. The inner housing may comprise a channel extending circumferentially around the inner housing, the channel being configured to collect any fluid leaking from within the inner housing. The outer housing may comprise at least one vent configured to receive any fluid collected in the channel and to direct the collected fluid in the channel to an exterior of the housing via the vent. 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 shows a schematic diagram of a motor unit comprising motor housing components; Figure 2 shows a cutaway of a portion of an outer housing; Figure 3 shows a cutaway of a portion of an inner housing; Figure 4 shows a cutaway of a portion of an inner housing received in an outer housing; Figure 5 shows a cutaway of a portion of an outer housing; Figure 6 shows a cutaway of a portion of an inner housing; Figure 7 shows a cutaway of a portion of an inner housing received in an outer housing; Figure 8 shows a cutaway of a portion of an outer housing; Figure 9 shows a cutaway of a portion of an inner housing; Figure 10 shows a cutaway of a portion of an inner housing received in an outer housing; Figure 11 shows a perspective view of a motor unit; Figure 12 shows a perspective view of a cutaway of an inner housing; and Figures 13 and 14 show schematic view of cutaways of portions of a motor unit. DETAILED DESCRIPTION These drawings should not be considered limiting, rather they are used for explaining and understanding the present disclosure. Figure 1 shows a motor unit 1 (which may comprise a motor and which may alternately be referred to as a motor). The motor unit 1 comprises a rotatable shaft 2 to which is coupled a rotor 3 of the motor unit, the rotor 3 being rotatable by virtue of its connection to the shaft 2. In this example, the rotor 3 is surrounded by a non-rotatable stator 4. In use, the shaft 2 is driven to rotate which causes the rotor 3 to rotate within the stator 4 for the motor unit 1 to generate power. The motor unit 1 in this example comprises a motor housing. Specifically, the motor unit 1 comprises an inner motor housing 100 and an outer motor housing 200. It will be appreciated that for this example motor unit 1, each of the inner and outer housings define an axial direction and a radial direction, each of the inner and outer housings extending circumferentially about a portion of the motor unit 1 (e.g. the shaft 2 and / or the rotor 3 and / or the stator 4). In this example the inner and outer housings are therefore circumferential. In this example the inner and outer housings are concentric. The inner housing 100 is configured to retain a portion of a motor therein, in this example the inner housing 100 is configured to retain a portion of the stator 4 therein, although in other examples the inner housing 100 may be configured to retain a portion of the rotor therein. In this example the inner housing 100 may therefore be a stator housing. The inner housing 100 may be a sleeve and may be a stator sleeve. The inner housing 100 is configured such that a region 7 is defined through which cooling fluid can flow to cool the portion of the motor (e.g. the stator 4 in this example). In some examples the cooling fluid is a gas and therefore the region 7 may be referred to as a gas chamber. It will be appreciated that the inner housing is configured such that the region surrounds at least a portion of the motor (e.g. the stator 4 in this example) such that the cooling fluid (e.g. a gas) can at least partially surround the portion of the motor to cool the motor. The region 7 may be circumferential, e.g. annular. As Figure 1 shows, the inner housing 100 is configured to be received in the outer housing 200, and the outer housing 200 is configured to receive the inner housing such that a fluid chamber 8 is formed around the inner housing 100. The fluid chamber 8 may be formed via abutment between at least a portion of the inner housing 100 and at least a portion of the outer housing 200. The fluid chamber 8 is configured to receive a cooling fluid to cool an outside, or exterior, or radially inward, surface of the inner housing 100. In some examples the cooling fluid is a liquid and therefore the fluid chamber 8 may be referred to as a liquid chamber. It will be appreciated that the outer housing 200 is configured such that the fluid chamber 8 surrounds at least a portion of the inner housing such that the cooling fluid (e.g. a liquid) can at least partially surround the portion of the inner housing 100 to cool the inner housing 100. The fluid chamber 8 may be a region of empty space between the inner housing 100 (that is to receive the stator 4) and the stator the outer housing 200. In other words, there may be direct mechanical contact between part of the outer housing 200 and part of the inner housing 100 but the geometry of the outer housing 200 may be such that the fluid chamber 8 is formed. The fluid chamber 8 may be referred to as a fluid channel. The fluid chamber 8 may be circumferential, e.g. annular. According to an example of the disclosure, and as will be described below, the outer housing 200 is configured such that any fluid leaking from within the inner housing 100 (e.g. any fluid leaking from within the region 7 through which cooling fluid, e.g. gas, flows) is directed to an exterior (e.g. an exterior region) 9 of the outer housing 200 and thereby prevented from entering the fluid chamber 8. The exterior 9 may also be an exterior, or exterior region, of the motor unit 1. According to an example of the disclosure, and as will be described below, the inner housing 100 is configured such that any fluid leaking from within the inner housing 100 (e.g. any fluid leaking from within the region 7 through which cooling fluid, e.g. gas, flows) is directed to the exterior 9 of the outer housing 200 and thereby prevented from entering the fluid chamber 8. Therefore, according to the present disclosure, any fluid leaking from within the inner housing 100 (e.g. from the region 7 through which cooling fluid flows) may be prevented from entering the fluid chamber 8 (thereby undesirably mixing with any fluid therein) by virtue of the configuration (e.g. the design or geometry thereof) of the outer housing 200, the configuration of the inner housing 100 (e.g. the design or geometry thereof) or the configuration of both the inner and outer housings (e.g. the interaction between both when the inner housing is received in the outer housing). It will be appreciated that due to the design of the inner and outer housings 100, 200 as presented in this disclosure they may be manufactured by die casting. The outer housing 200 may be referred to as a motor housing and there may be a die cast motor housing. The inner housing 100 may be a sleeve and therefore may be a die cast sleeve. The inner housing 100 may be considered a stator sleeve or a stator housing. The inner and outer housings 100, 200 may comprise Aluminium, e.g. may be formed by pouring molten Aluminium into moulds (e.g. steel moulds). It will be appreciated that the inner and outer housings according to the present disclosure effectively deal with any leakages that may occur. Leakages may be due, for example due, to the inner and outer housings being manufactured by means of a die casting process. For instance, even when the inner and outer housings are die cast the motor unit in use may produce a minimum leakage. This may be around 2 grams per year (even when O-rings are used as internal seals) and it will be appreciated that this may accumulate over time when no methods for mitigating it are provided for. Accumulated leakage may not be identifiable (e.g. there may not be any way of sensing it) and may not be measurable (e.g. it may not be possible to determine how much fluid has leaked), and therefore over a long period of time accumulated leakage may cause a number of issues, one of which will be now explained by way of example (although the skilled person will understand that mitigating any negative effects of leakage may be desirable in any implementation). In an example implementation the motor unit 1 is a motor for a compressor. In this example the fluid surrounding the stator 4 within the inner housing 100 may be a refrigerant gas and it may be located in the region 7 due to leakage from the compressor. Put another way, fluid (e.g. refrigerant gas) from the first and / or second compressor stages may bleed, or leak into the motor cavity and be present in the region 7 where it functions to cool the motor (e.g. the stator thereof in the Figure 1 example). The fluid in the chamber 8 may be a liquid, e.g. a coolant, e.g. water. Such a cooling fluid may be introduced into the motor unit 1 to cool the housing, and may be introduced by a pump, e.g. a coolant pump. This may be part of a closed loop system and therefore fluid (e.g. coolant such as water) may be continually circulated (or recirculated) through the fluid chamber 8 to cool the inner housing 100 and therefore the motor components when the motor is in use. As such, the fluid chamber 8 may be referred to as a coolant loop. If refrigerant gas (from the region 7) were to leak into the fluid chamber 8 then this introduces refrigerant gas into the coolant loop. Refrigerants may be flammable. The inner housing of the fluid chamber 8 may not be treated or coated (e.g. with an anti-corrosion substance) and therefore leaked refrigerant in the fluid chamber may cause corrosion in the interior walls of the coolant loop. Furthermore, it may not be known how a mixture containing both refrigerant gas and water reacts with copper or slag etc. Even further, if the fluid chamber 8 were to be damaged then this may lead to a potentially flammable substance escaping into the atmosphere. Therefore, potentially unavoidable small leakages accumulating over time may cause problems if not accounted for. The present disclosure addresses such potential problems and example ways of configuring the outer housing 200 and the inner housing 100 such that fluid leaking from within the inner housing is prevented from entering the fluid chamber 8 will now be described. Examples of inner and outer housings will now be described with reference to Figures 2-4, Figure 2 showing an outer housing configured to receive the inner housing of Figure 3, Figure 3 showing an inner housing configured to be received in the outer housing of Figure 2, Figure 4 showing the inner housing of Figure 3 received in the outer housing of Figure 2. Figure 2 shows one example configuration of the outer housing 200. The outer housing 200 of the Figure 2 example is configured such that any fluid leaking from within the fluid chamber 8 is directed to an exterior of the outer housing via a gap between the outer housing 200 and the inner housing 100 when the inner housing is received in the outer housing 200 (see Figure 4). To create the gap the outer housing 200 is configured such that a main housing portion comprises a terminal portion, or side wall, or end wall, 8a that is configured to abut a flange (e.g. a radially outwardly protruding flange) of the inner housing 100. The gap formed therebetween is therefore the result of the seal between the inner and outer housings 100, 200 being imperfect, however the geometry of the outer housing 200 in this example ensures that any fluid in the fluid chamber 8 that does leak (e.g. through any gaps between the inner and outer housings 100, 200) is directed away from the fluid chamber 8 (see Figure 4). The configuration of the outer housing 200 in this example is such that any fluid leaking from the fluid chamber 8 is directed axially and then radially outwardly from the outer housing 200. The configuration of the outer housing 200 in this example is such that any fluid leaking from the fluid chamber 8 is directed to the region 9 external to the outer housing. It will therefore be appreciated that the configuration of the outer housing 200 ensures that any fluid leaking from the fluid chamber 8 is not permitted to mix with any fluid in any other part of the motor unit 1. This ensures that any fluid that has leaked from within the inner housing 100 is directed away from the fluid chamber 8 and to an exterior 9 region of the outer housing, which in turn prevents any fluid leaking from within the inner housing 100 from mixing with fluid in the fluid chamber 8. As shown in Figure 2, the left-hand side of the outer housing 200 has a similar structure to the right-hand side (left / right being with reference to what is shown in Figure 2). Thus, in the Figure 2 example, the outer housing 200 is configured such that any fluid leaking from within the fluid chamber 8 is directed to an exterior of the outer housing via a gap g1 between a first surface 8a of the outer housing 200 and a first surface of the inner housing 100 when the inner housing is received in the outer housing 200 and via a gap g2 between a second surface 8b of the outer housing 200 and a second surface of the inner housing 100 when the inner housing is received in the outer housing 200. Put another way, the outer housing 200 is configured such that two axially spaced-apart gaps exist between the outer housing 200 and the inner housing 100 via which any fluid leaking from the fluid chamber 8 is directed to an exterior region 9 of the outer housing (e.g. directed radially outwards). Although the Figure 2 arrangement shows an approximately axially symmetric arrangement in terms of how the outer housing 200 is configured to direct leaking fluid to the exterior of the outer housing, it will be appreciated that in examples the structure of the lefthand side may not be equal to the right-hand side; put another way, the geometry and / or configuration of each sides may be such that leaking fluid is directed to the exterior of the outer housing in different ways. The inlet 210 for the fluid chamber 8 is also shown in Figure 2 via which cooling fluid may enter the fluid chamber 8 and therefore the motor unit 1. The cooling fluid (e.g. a liquid) may enter the fluid chamber 8 via the inlet 210 where it flows through the circumferential fluid chamber 8 surrounding the inner housing 100 and exits the outer housing 200 and motor unit 1 via a (not shown) outlet. Figure 3 shows one example configuration of the inner housing 100 such that fluid leaking from within the inner housing is prevented from entering the fluid chamber 8. The inner housing of this example comprises a flange 101a configured to direct any fluid leaking from within the inner housing (e.g. from the region 7) to the region 9 external to the outer housing when the inner housing is received in the outer housing, and external to the motor unit 1. The flange 101a comprises an extension in the radial direction (e.g. a radially outward extension) of the inner housing 5, e.g. away from an inner housing body. It will be appreciated from Figure 3 that the flange 101 a is also configured to direct any fluid leaking from within the fluid chamber 8 to the region 9 external to the outer housing when the inner housing is received in the outer housing. In this example the flange 101a therefore serves two purposes (in that it directs both fluid from within the inner housing and fluid from within the fluid chamber 8 to the exterior 9). However in some examples the inner housing 100 may comprise first and second flanges, the first flange being configured to direct any fluid leaking from within the inner housing to the region 9, and the second flange being configured to direct any fluid leaking from within the fluid chamber 8 to the region 9. As shown in Figure 3, the left-hand side of the inner housing 100 has a similar structure to the right-hand side (left / right being with reference to what is shown in Figure 3). Thus, in the Figure 3 example, any fluid leaking from within the inner housing (and within the fluid chamber 8) is directed to an exterior of the housing via a first flange 101a and a second flange 101b. Put another way, the inner housing 100 comprises two axially spaced-apart flanges 101a, 101b that are each configured to direct any fluid leaking from within the inner housing and / or from within the fluid chamber 8 to the region 9 exterior of the housing. As for Figure 2, although the Figure 3 arrangement shows an approximately axially symmetric arrangement in terms of how the inner housing 100 is configured to direct leaking fluid to the exterior of the outer housing, it will be appreciated that in examples the structure of the left-hand side may not be equal to the right-hand side; put another way, the geometry and / or configuration of each sides may be such that leaking fluid is directed to the exterior of the outer housing in different ways. Figure 4 shows part of a motor unit 1 wherein the inner housing 100 of Figure 3 is received in the outer housing 200 of Figure 2 such that the fluid chamber 8 is formed around the inner housing 100 to receive the fluid for cooling the inner housing 100. It will be appreciated that via the side surfaces 8a, 8b of the outer housing 200 and the flanges 101a, 101b of the inner housing 5, fluid leaking from within the inner housing 100 (e.g. from the region 7 thereof) and fluid leaking from the fluid chamber 8 are prevented from mixing, and directed outside of the outer housing and outside of the motor unit 1, via the gaps g 1, g2 formed between the respective side surfaces 8a, 8b of the outer housing 200 and the flanges 101a, 101b of the inner housing 100. Examples of inner and outer housings will now be described with reference to Figures 5-7, Figure 5 showing an outer housing configured to receive the inner housing of Figure 6, Figure 6 showing an inner housing configured to be received in the outer housing of Figure 5, Figure 7 showing the inner housing of Figure 6 received in the outer housing of Figure 5. Figure 5 shows one example configuration of an outer housing 200 is configured such that any fluid leaking from within the fluid chamber 8 is directed to an exterior 9 of the outer housing via a vent 211a in the outer housing 200. The vent 211a extends through the housing from an interior or inner portion to an exterior or outer portion to connect the inner portion of the outer housing to the exterior of the housing 9. As shown in Figure 5, the outer housing 200, specifically the vent 211a thereof, is configured such that any fluid leaking from within the inner housing 100 (e.g. from the region 7) is directed outside the outer housing 200 via the vent 211a. Furthermore, the vent 211a is configured such that any fluid leaking from within the fluid chamber 8 is directed to an exterior 9 of the outer housing via the vent 211a. However, as will be described later the outer housing may comprise a respective vents to direct any fluid leaking from within the inner housing and from the fluid chamber 8 to the region 9 exterior of the housing. The outer housing 200 in this example comprises a first vent 211a at a first axial position and a second vent 211b at a second axial position. Each vent 211a, 11b is configured such that any fluid leaking from within the inner housing and from within the fluid chamber 8 is directed to the exterior 9 of the outer housing via the respective vents. In general, the outer housing 6 may comprise a plurality of vents. They may be spaced apart axially (as shown in Figure 5) but may in addition to or alternatively be circumferentially spaced apart. Although the vent 211a that is configured to direct both any fluid leaking from within the inner housing 100 and from the fluid chamber 8 to the exterior 9 of the outer housing 200, however in some examples the outer housing 200 may comprise two vents that may be configured such that any fluid leaking from within the inner housing 100 (e.g. gas) is directed to the exterior 9 of the outer housing 200 via a first vent and that any fluid leaking from the fluid chamber 8 (e.g. liquid) is directed to the exterior 9 of the outer housing 200 via a second vent. These vents may therefore be termed a gas vent and a liquid vent in some examples. The first and second vents may be side by side. The outer housing 200 may therefore comprise at least one set of vents, or a plurality of sets of vents, a respective first vent in each set for receiving leaking fluid from within the inner housing and a respective second vent in each set for receiving leaking fluid from the fluid chamber. The outer housing may therefore comprise a first set of vents on a left-hand side thereof and a second set of vents on a righthand side thereof, each set comprising first and second vents as described above to receive the respective leaks from within the inner housing and from within the fluid chamber. As for Figures 2 and 3, although the Figure 5 arrangement shows an approximately axially symmetric arrangement in terms of how the outer housing 200 is configured to direct leaking fluid to the exterior of the outer housing, it will be appreciated that in examples the structure of the left-hand side may not be equal to the right-hand side; put another way, the geometry and / or configuration of each sides may be such that leaking fluid is directed to the exterior of the outer housing in different ways. Figure 6 shows one example configuration of the inner housing 100. The inner housing 100 of this example comprises a channel 112a. The channel 112a is configured to collect (or accumulate, the terms may be used interchangeably) any fluid leaking from within the inner housing (e.g. from the region 7 thereof). The channel 112a is also configured to collect any fluid leaking from the fluid chamber 8. The channel 112a may also minimise the possibility of internal clogging since any large slurries or dust particles inside the motor unit 1 may be collected into the channel (and therefore vented to the atmosphere in examples where the outer housing 200 comprises the vent). In some examples (shown in Figure 12), the channel 112a is a circumferential channel. In these examples the channel 112a may extend the entire circumference of the inner housing 100. The inner housing 100 in this example comprises a first channel 112a at a first axial position and a second channel 112b at a second axial position. Each channel 112a, 12b is configured such that any fluid leaking from within the inner housing and from within the fluid chamber 8 is collected in the channel. Each channel 112a, 12b may be a circumferential channel. Each channel 112a, 12b may extend the entire circumference of the inner housing 5. Figure 5 shows a channel 112a that is configured to collect both any fluid leaking from within the inner housing 100 and fluid leaking from the fluid chamber 8, however in some examples the inner housing 100 may comprise two channels that may be configured such that any fluid leaking from within the inner housing 100 is collected in a first channel and that any fluid leaking from the fluid chamber 8 is collected in a second channel. Such channels may therefore be termed a gas collection channel and a liquid collection channel. The first and second channels may be side by side. The inner housing 100 may therefore comprise at least one set of channels, or a plurality of sets of channels, a respective first channel in each set for collecting leaking fluid from within the inner housing and a respective second channel in each set for collecting leaking fluid from the fluid chamber. The inner housing may therefore comprise a first set of channels on a left-hand side thereof and a second set of channels on a right-hand side thereof, each set comprising first and second channels as described above to receive the respective leaks from within the inner housing and from within the fluid chamber. It will be appreciated a channel of the inner housing may be associated with a vent of the outer housing so that fluid collected in the channel is vented to the atmosphere (e.g. the exterior 9) via the vent. As for Figures 2, 3, and 5, although the Figure 6 arrangement shows an approximately axially symmetric arrangement in terms of how the inner housing 100 is configured to direct leaking fluid to the exterior of the outer housing, it will be appreciated that in examples the structure of the left-hand side may not be equal to the right-hand side; put another way, the geometry and / or configuration of each sides may be such that leaking fluid is directed to the exterior of the outer housing in different ways. Figure 7 shows part of a motor unit 1 wherein the inner housing 100 of Figure 6 is received in the outer housing 200 of Figure 5 such that the fluid chamber 8 is formed around the inner housing 100 to receive the fluid for cooling the inner housing 100. Figure 7 shows the possible interrelationship between a vent 211 and a channel 112 when an outer housing 200 having the vent 211 and an inner housing 100 having the channel 112 are used in combination. It will be apparent from Figure 7 that the channel 112 acts as a leak collection chamber by collecting any leaked fluid (e.g. gas and / or liquid) from an interior of the inner housing 100 and from the fluid chamber 8 and the vent 211 acts as a relief channel to vent the collected fluid (e.g. gas and / or liquid) into the atmosphere at ambient pressure. Figure 8 shows one example configuration of the outer housing 200. In this example, the outer housing 200 at a first axial position (corresponding to the left-hand side of the figure) is configured such that any fluid leaking from within the fluid chamber 8 is directed to an exterior of the outer housing via a gap between the outer housing 200 and the inner housing 100 when the inner housing is received in the outer housing 200, as described above with respect to Figure 2, and at a second axial position (the right-hand side of the figure) the outer housing 200 comprises a vent and is configured such that any fluid leaking from within the fluid chamber 8 or within the inner housing is directed to an exterior 9 of the outer housing via the vent 211, as described above with respect to Figure 5. Figure 9 shows one example configuration of the inner housing 100. In this example, the inner housing 100 at a first axial position (corresponding to the left-hand side of the figure) comprises a flange configured to direct any fluid leaking from within the inner housing (e.g. from the region 7) and any fluid leaking from the fluid chamber 8 to the region 9 external to the outer housing, as described above with respect to Figure 3, and at a second axial position (the right-hand side of the figure) the inner housing 100 comprises a channel configured to collect any fluid leaking from within the inner housing (e.g. from the region 7 thereof) and to collect any fluid leaking from the fluid chamber 8, as described above with respect to Figure 6. Figure 10 shows part of a motor unit 1 wherein the inner housing 100 of Figure 10 is received in the outer housing 200 of Figure 9 such that the fluid chamber 8 is formed around the inner housing 100 to receive the fluid for cooling the inner housing 100. It will be appreciated that the geometry of both housings are such that, on the left hand side, any fluid leaking from within the inner housing and from within the fluid chamber 8 is directed to the exterior 9 by virtue of the flange of the inner housing and via a gap, respectively as described above with respect to Figure 4, and that on the right hand side, the interaction between the channel to collect leaked fluid prevents it from leaking into the fluid chamber 8 and the vent vents the collected leakage fluid to the exterior 9 to prevent internal leakage is as described above with respect to Figure 7. Figure 11 shows a perspective view of the motor unit 1. The exterior surface 220 of the outer housing 200 is shown, specifically showing the vent 211 of the outer housing 200. In this example one vent 211 is shown but the outer housing 200 may comprise more than one vent or any number of sets of vents etc. as described above depending on the implementation. Through the vent 211, a circumferential channel 112 of the inner housing 100 is shown. Figure 12 shows a schematic perspective view of part of an inner housing 100 illustrating a circumferential channel 112, the inner housing 100 of Figure 12 may be the inner housing shown in Figure 11. It will be appreciated that the channel 112 extends the circumference (e.g. the entire circumference) of the inner housing 100. The channel 112 may therefore be referred to as an annular channel although in other examples the channel may not extend the entire circumference. The channel 112 may be of any suitable shape to collect leaked fluid. It will be appreciated that in examples, such as depicted in Figures 11 and 12, the channel 112 may extend the entire circumference of the inner housing but the vent may not. This means that fluid is effectively collected in the annular channel, or collection chamber 112 where it is permitted to travel around the circumference of the housing via the channel until it reaches a vent where it is vented outside the housing and into the atmosphere. Because of the lower pressure of the atmosphere relative to the interior portions, leaked fluid will be drawn through and around the channel 112 and drawn out of the vent 211 into the atmosphere. Indeed, in examples not using the channel or vent, the pressure difference will cause fluid from the interior of the housing to be drawn to the atmosphere. Figures 13 and 14 show cross-sections through different radial parts of the motor unit 1. Figure 13 shows a cross-section through a radial part of the outer housing 200 where the vent 211 is located whereas Figure 14 shows a cross-section through a radial part of the outer housing 200 where the vent 211 is not located. It will be appreciated that any leaked fluid collected in the channel at the portion of the channel shown in Figure 14 will be drawn around the through the channel to the point shown in Figure 13 where the pressure differential will cause it to travel through the vent 211 and out into the atmosphere / exterior region. Referring back to Figure 1, it will be seen that the outer housing 200 comprises a first vent 211a at a first axial position (or location) and a second vent 211b at a second axial position (or location) and the inner housing 100 comprises a first channel 112a at the first axial position and a second channel 112b at the second axial position. As described above with respect to Figures 5-7, it will be appreciated that any fluid leaking from within the inner housing 100 (e.g. from the region 7 which may contain gas) and any fluid leaking from within the fluid chamber 8 defined by the outer housing 200 may be collected in either the channel 112a or 112b depending on the route the leak fluid takes, which is then vented to the atmosphere 9 via a respective vent 211a, 211b as described above. Examples of this disclosure may also configure the inner housing 100 to receive at least one sealing element to enhance the sealing of the motor unit 1. For example, the inner housing 100 may be configured to receive at least one O-ring, for example the inner housing body may be configured to comprise at least one groove configured to receive an O-ring. It will be appreciated that when the inner housing 100 is configured to receive an O-ring (O-rings being circumferential), the groove to receive the O-ring may also be circumferential. Examples of this will now be described. Still referring to Figure 1, the inner housing 100 comprises circumferential grooves 131a-d configured to respectively receive circumferential O-rings 12a-d. It will be seen in this example that the inner housing comprises two grooves 131a and 131b on either side of the first channel 112a, and two grooves 131c and 131d on either side of the second channel 112b to seal the channel. Referring again to Figure 4, the inner housing 100 comprises grooves 131a-d configured to respectively receive O-rings 12a-d. Groove 131a is located on the first flange 101a and groove 131 d is located on the second flange 101b. Grooves 131b and 131c are located on a body of the inner housing 100 and are configured to face the outer housing, away from a centre of the motor unit, radially outwardly. Grooves 131a and 131 d are perpendicular to grooves 131b and 131c. Grooves 131b and 131c are located on either side of the fluid chamber 8. Referring again to Figure 7, the inner housing 100 comprises grooves 131a-d configured to respectively receive O-rings 12a-d. Grooves 131a-d are located on a body of the inner housing 100 and are configured to face the outer housing away from a centre of the motor unit, radially outwardly. Grooves 131a and 131b are located on either side of the first channel 112a and grooves 131c and 131 d are located on either side of the second channel 112b. Referring again to Figure 10, the inner housing 100 comprises grooves 131a-d configured to respectively receive O-rings 12a-d. Groove 131a is located on the first flange 101a and grooves 131b, 131c, and 131 d are located on a body of the inner housing 100 and are configured to face the outer housing, away from a centre of the motor unit, radially outwardly. Groove 131a is perpendicular to grooves 131b, 131c, and 131d. Grooves 131c and 131 d are located on either side of the channel. The skilled person will appreciate that any combination of the grooves to receive an O-ring may be possible depending on the example. For example, if the inner housing 100 comprises two spaced-apart channels, one for collecting leaked fluid from within 7 the inner housing, the other for collecting leaked fluid from within the fluid chamber 8, then the inner housing 100 may comprise a groove for receiving an O-ring, the groove located in between the first and second channels, in addition to two grooves on either side of the set of channels. The present disclosure provides for a cost-effective, efficient, and easy to manufacture in a batch process (e.g. in large quantities) motor housing components. The present disclosure provides inner and outer motor housings that can be manufactured as part of a batch process using die casting however the geometries of the inner and outer motor housings are such that any fluid leaking from within the motor unit is directed outside of the motor housing, taking advantage of the pressure difference between the inside and the outside of the motor housing, reducing the problems that could occur with any leak or bleed or parasitic fluid flow. 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 drawings, the disclosure, and the appended claims.

Claims

1. An outer housing for a motor, the outer housing configured to receive an inner housing such that a portion of the outer housing abuts a portion of the inner housing to form a fluid chamber around the inner housing to receive a fluid for cooling the inner housing, wherein the outer housing is configured such that any fluid leaking from within the inner housing is directed to an exterior of the outer housing and thereby prevented from entering the fluid chamber.

2. The outer housing of claim 1, wherein the outer housing is configured such that any fluid leaking from within the fluid chamber is directed to an exterior of the outer housing via a gap between the outer housing and the inner housing when the inner housing is received in the outer housing.

3. The outer housing of any preceding claim, wherein the outer housing comprises a vent extending through the housing to connect an inner portion of the outer housing with an exterior of the outer housing, the outer housing being configured such that any fluid leaking from within the fluid chamber is directed to an exterior of the outer housing via the vent.

4. The outer housing of claim 3, the outer housing being configured such that any fluid leaking from within the inner housing is directed outside the outer housing via the vent.

5. The outer housing of claim 3 or 4, wherein the outer housing comprises first and second vents, each vent extending through the housing to connect an inner portion of the outer housing with a region outside the outer housing, the outer housing being configured such that any fluid leaking from within the fluid chamber is vented outside the outer housing via the first vent, and any fluid leaking from within the inner housing is vented outside the outer housing via the second vent.

6. The outer housing of any of claims 3 or 4, wherein the housing comprises a plurality of vents.

7. The outer housing of claim 6, wherein the plurality of vents are spaced-apart in a circumferential direction of the outer housing.

8. An inner housing for a motor, the inner housing configured to retain a portion of a motor therein, the inner housing defining a region through which cooling fluid can flow to cool the motor therein, the inner housing configured to be received in an outer housing such that a portion of the inner housing abuts a portion of the outer housing to form a fluid chamber around the inner housing to cool an outside surface of the inner housing, wherein the inner housing is configured such that any fluid leaking from within the inner housing is directed to an exterior of the outer housing and thereby prevented from entering the fluid chamber.

9. The inner housing of claim 8, wherein the inner housing comprises a channel configured to collect any fluid leaking from within the inner housing.

10. The inner housing of claim 8 or 9, wherein the inner housing comprises a channel configured to collect any fluid leaking from the fluid chamber.

11. The inner housing of claim 9 or 10, wherein the channel extends in a circumferential direction of the inner housing.

12. The inner housing of any of claims 8-11, wherein the inner housing comprises a flange configured to direct any fluid leaking from within the inner housing to a region external to the outer housing when the inner housing is received in the outer housing.

13. The inner housing of any of claims 8-12, wherein the inner housing comprises a flange configured to direct any fluid leaking from within the fluid chamber to a region external to the outer housing when the inner housing is received in the outer housing.

14. A motor unit comprising an outer housing as claimed in any of claims 1-7 and an inner housing as claimed in any of claims 8-13, wherein the inner housing is received in the outer housing such that the fluid chamber is formed around the inner housing to receive the fluid for cooling the inner housing.

15. A motor unit as claimed in claim 14 wherein the inner housing comprises a channel extending circumferentially around the inner housing, the channel being configured to collect any fluid leaking from within the inner housing, and wherein the outer housing comprises at least one vent configured to receive any fluid collected in the channel and to direct the collected fluid in the channel to an exterior of the housing via the vent.

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