TECHNICAL FIELD The present disclosure relates to a drive assembly for a vehicle. In particular, but not exclusively it relates to a drive assembly for a road vehicle, such as a car.

Aspects of the invention relate to a drive assembly, a vehicle and a method. BACKGROUND

It is known to provide a subframe for a vehicle which comprises two longitudinal members configured to be attached to a vehicle body shell and a cross-member, which connects the two longitudinal members and which houses a drive component such as an electric motor. A problem with the arrangement is that the construction of the subframe is quite complex being formed of several different components, including the two longitudinal members and the cross-member, which are bolted together. A second problem is that the subframe has to be dismantled to access the electric motor. It is an aim of the present invention to address disadvantages of the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a drive assembly, a vehicle and a method as claimed in the appended claims.

According to an aspect of the invention there is provided a drive assembly for a vehicle the drive assembly comprising: a drive mechanism having two output shafts for connection to wheels of the vehicle; a subframe having at least a first mounting feature for mounting the drive assembly at a first side of the body of the vehicle at least a second mounting feature for mounting the drive assembly at a second side of the body of the vehicle; and a removable cover attached to the subframe and covering at least a part of the drive mechanism; wherein the subframe comprises a continuous component extending from the first mounting feature to the second mounting feature and the continuous component has a hole or recess in which at least a part of the drive mechanism resides. This provides the advantage that the drive mechanism may be supported within the hole or recess of the single continuous component of the subframe, which transfers loads from the drive mechanism to the body of the vehicle in which it is installed. In this way, the number of components and component interfaces is reduced, and so it becomes possible to reduce weight and space taken up within a vehicle. In addition, installation and/or replacement of the drive mechanism is facilitated by having a removable cover.

In some embodiments the continuous component comprises a continuous piece of cast metal or a continuous sheet of pressed metal.

The term "metal" as used herein will be understood to mean either a pure metal or a metal alloy. In some embodiments the drive assembly may comprise a container located within the hole or recess and a seal is provided between the removable cover and the container to enable lubricant to be contained by the removable cover and the container in combination. This provides the advantage that the continuous component does not have to be configured to retain the lubricant and consequently it may be provided with a lighter structure comprising holes.

In some embodiments the continuous component of the subframe has a recess in which at least a part of the drive mechanism resides, and the drive assembly comprises a seal between the removable cover and the subframe to enable lubricant to be contained by the removable cover and subframe in combination.

The drive mechanism may comprise an electric motor. Alternatively, the drive mechanism may comprise a differential having an input shaft for connection via a driveshaft to an engine mounted remotely from the drive mechanism.

In some embodiments the removable cover comprises a plastics material and/or the drive assembly comprises a container located within the hole or recess and the container is formed of a plastics material. This provides the advantage that the drive assembly may be made lighter in weight while maintaining the required strength through the continuous component of the subframe. The drive assembly comprises a support located over the removable cover, the support being attached to the continuous component of the subframe. By having a removable cover and a separate support provides the advantage that the cover may be formed of a lightweight material such as a polymer that is only required to maintain the presence of a lubricant around the drive mechanism, while the support may be designed solely to provide mechanical strength to support the removable cover or provide additional strength to the subframe. In some embodiments the drive assembly comprises bearings supporting the output shafts and the bearings are located between the removable cover and the subframe. By locating the bearings between the removable cover and the subframe simplifies assembly of the drive assembly. In some embodiments the removable cover comprises a plastics material and a metallic structure embedded in the plastics material adjacent to the bearings; and/or the drive assembly comprises a container located within the hole or recess, and the container comprises a plastics material with a metallic structure embedded in the plastics material adjacent to the bearings. This composite structure enables loads to be transferred between the bearings of the drive mechanism and the mounting features while allowing the removable cover and/or the container to be formed of a relatively lightweight (plastics) material.

In some embodiments the continuous component defines bearing surfaces for receiving the bearings.

In some embodiments the subframe has at least a first two mounting features for mounting the drive assembly, at a first side of the body of the vehicle, and at least a second two mounting features for mounting the drive assembly at a second side of the body of the vehicle.

In some embodiments the subframe has a third mounting feature for mounting the drive assembly to the body fore or aft of the drive mechanism. This has the advantage of minimizing the number of fixings necessary to mount the subframe to the body. According to another embodiment of the invention there is provided a vehicle comprising a body and a drive assembly mounted on the body at least the first mounting feature and the second mounting feature. According to another embodiment of the invention there is provided a method of mounting a drive mechanism, the drive mechanism having two output shafts for connection to wheels of a vehicle the method comprising: positioning at least a part of a drive mechanism within a hole or a recess formed in a continuous component of a subframe, the continuous component having at least a first mounting feature for mounting the drive assembly at a first side of a body of a vehicle, and at least a second mounting feature for mounting the drive assembly at a second side of the body of the vehicle; and attaching a removable cover to the subframe, the removable cover covering at least a part of the drive assembly.

In some embodiments the continuous component comprises a continuous piece of cast metal or a continuous sheet of pressed metal.

In some embodiments the method comprises positioning a container within the hole or the recess and providing a seal between the removable cover and the container to enable lubricant to be contained by the removable cover and container in combination.

In some embodiments the continuous component of the subframe has a recess in which at least a part of the drive mechanism resides; and the drive assembly comprises a seal between the removable cover and the continuous component to enable lubricant to be contained by the removable cover and continuous component in combination.

The drive mechanism may comprise an electric motor. Alternatively, the drive mechanism may comprise a differential.

In some embodiments the removable cover comprises a plastics material.

In some embodiments the method comprises positioning a support over the removable cover and attaching the support to the continuous component of the subframe. In some embodiments the drive assembly comprises bearings supporting the output shafts and the method comprises positioning the bearings between the removable cover and the subframe. In some embodiments the removable cover comprises a plastics material and metallic structure embedded in the plastics material to provide reinforcement of the plastics material, and the method comprises positioning a part of the removable cover comprising the metallic structure over the bearings. In some embodiments the method comprises positioning the bearings within bearing surfaces defined by the continuous component of the subframe.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 shows a vehicle 103 comprising a car that has a drive assembly 101 ;

Fig. 2 shows a top view of an example of the drive assembly 101 of Fig. 1 ;

Fig. 3 shows a cross-sectional side view of the drive assembly 101 of Fig. 2;

Fig. 4 shows a bottom view of the drive assembly 101 of Fig. 2;

Fig. 5 shows a cross-sectional view of the drive assembly 101 at plane "A" shown in Fig. 2;

Fig. 6 shows a cross-sectional view of the drive assembly 101 at plane "B" shown in Fig. 2;

Fig. 7 shows an end view of the drive assembly 101 in the direction of arrow C in Fig. 2;

Fig. 8 shows a top view of an alternative example of the drive assembly 101 of Fig. 1 ;

Fig. 9 shows a cross-sectional side view of the drive assembly 101 of Fig. 8; Fig. 10 shows a cross-sectional view of the drive assembly 101 at plane "D" shown in Fig. 8; Fig. 1 1 shows a top view of a second alternative example of the drive assembly 101 of Fig. 1 ;

Fig. 12 shows a cross-sectional side view of the drive assembly 101 of Fig. 1 1 ;

Fig. 13 shows a second cross-sectional view of the drive assembly 101 at plane "E" shown in Fig. 1 1 ;

Fig. 14 shows a third cross-sectional view of the drive assembly 101 at plane "F" shown in Fig. 1 1 ;

Fig. 15 shows a flow-chart outlining a method 1500 of mounting a drive mechanism 104; Fig. 16 shows schematically a second vehicle 1603 comprising a rear-wheel-drive car that has a drive assembly 101 A;

Fig. 17 shows a top view of an example of the drive assembly 101 A of Fig. 16;

Fig. 18 shows a cross-sectional side view of the drive assembly 101 A of Fig. 17;

Fig. 19 shows a second cross-sectional view of the drive assembly 101 A at plane "G" shown in Fig. 17;

Fig. 20 shows a bottom view of a drive assembly; and

Fig. 21 shows a cross section taken at plane "H" shown in Fig.20.

DETAILED DESCRIPTION

The Figures illustrate a drive assembly 101 , 101 A for a vehicle 103, 1603, the drive assembly 101 , 101 A comprising: a drive mechanism 104 having two output shafts 1 13 for connection to wheels 105A of the vehicle 103; a subframe 106, 106A, 106B, 106C having at least a first mounting feature 107 for mounting the drive assembly 101 , 101 A at a first side of the body 102, 1602, at least a second mounting feature 108 for mounting the drive assembly 101 , 101 A at a second side of the body 102, 1602; a removable cover 208, 208A attached to the subframe 106, 106A, 106B, 106C and covering at least a part of the drive mechanism 104, 104A; wherein the subframe 106, 106A, 106B, 106C comprises a continuous component 1 10, 1 10A extending from the first mounting feature 107 to the second mounting feature 108.

In the various embodiments described below, the continuous component 1 10, 1 1 OA comprises a continuous piece of cast metal or a continuous sheet of pressed metal. The continuous component 1 10, 1 1 OA may be formed of a metal such as steel or aluminium alloy. A vehicle 103 comprising a car that has a drive assembly 101 is shown schematically in Fig. 1 . In the present example, the car 103 has an engine 1 1 1 which drives front wheels 105B via a transmission 1 12. The car 103 also has rear wheels 105A that are separately driven by a drive mechanism 104 comprising an electric motor 1 14 that forms a part of the drive assembly 101 .

The drive mechanism 104 is mounted on a subframe 106, which has a first two mounting features 107 for mounting the drive assembly 101 at a first side of the body 102 of the car 103 and a second two mounting features 108 for mounting the drive assembly 101 at a second side of the body 102. The mounting features 107 and 108 may comprise holes for receiving bushings 1 18 of known types. The bushings 1 18 may be attached to longitudinal beams 120 defined by the body 102 and which extend towards the rear of the vehicle 103. It may be noted that the body 102 may be referred to as a "body in white" or "body shell" and it comprises several pressed metal panels that are welded together.

Although the subframe 106 has a first two mounting features 107 for mounting the drive assembly 101 at a first side of the body 102 of the car 103 and a second two mounting features 108 for mounting the drive assembly 101 at a second side of the body 102, in alternative embodiments, the drive assembly 101 may have a first single mounting feature 107 for mounting the drive assembly 101 at a first side of the body 102 of the car 103 and a second single mounting feature 108 for mounting the drive assembly 101 at a second side of the body 102. In such embodiments, the subframe 106 may be provided with a third mounting feature arranged to be fixed to the body 102 of the car 103, either fore or aft of the drive mechanism, so that the first mounting feature 107, the second mounting feature 108 and the third mounting feature are positioned at the corners of a triangle. The subframe may comprise a continuous component extending between each of the first, second and third mounting features. The third mounting feature may be positioned in the vicinity of a centerline of the body 102 and closer to the centerline than it is to either of the first or second mounting features. Typically, the third mounting feature is positioned on the centerline of the body 102.

The subframe 106 of Fig. 1 comprises a continuous component 1 10 extending from the first two mounting features 107 to the second two mounting features 108 and is formed as a single cast component. However, in an alternative embodiment the subframe is formed of a single sheet of metal that is cut, for example by laser, and pressed to form the required shape.

The drive mechanism 104 has two output shafts 1 13, each of which is connected to a respective rear wheel 105A via universal joints (illustrated by the dashed outline 1 15), a driveshaft (or halfshaft) 1 16 and wheel axles 1 17. The wheel axles 1 17 may be operatively connected to the subframe 106 by a suspension mechanism (not shown) to support the body 102 of the car 103. In the present example, the front wheels 105B are independently driven from the rear wheels 105A. However, in alternative embodiments, the vehicle 103 is solely powered by a drive mechanism 104 comprising an electric motor that drives the rear wheels 105A. In other alternative embodiments, the subframe 106 is mounted on longitudinal beams located towards the front of the vehicle 103 and a drive mechanism 104 comprising an electric motor that drives the front wheels 105B is mounted on the subframe 106. In another alternative embodiment, that will be described in further detail below with regard to Figs. 16 to 19, a subframe 106C is arranged to be mounted towards the rear of a vehicle 1603, and the drive mechanism 104 comprises a differential that is driven by an engine mounted at the front of the vehicle 1603.

An example of the drive assembly 101 of Fig. 1 is shown in Figs. 2, 3, 4, 5, 6 and 7. Fig. 2 shows a top view of the drive assembly 101 ; Fig. 3 shows a cross-sectional side view; Fig. 4 shows a bottom view; Figs. 5 and 6 show cross-sectional views at planes A and B illustrated in Fig. 2; and Fig. 7 shows an end view in the direction of arrow C in Fig. 2.

As may be seen in Figs. 2 and 3, the drive mechanism 104 comprises an electric motor 1 14 that has a stator 201 , which may comprise coils, and a rotor 202, which may comprise permanent magnets mounted on a hollow shaft 203. The hollow shaft 203 is operatively connected to a gear and differential mechanism 204 which is arranged to provide equal torque to each of the two output shafts 1 13. The gear and differential mechanism 204 may comprise epicyclical gearing providing a required gear ratio of, for example, 9:1 .

A first one of the two output shafts 1 13 is supported by a bearing 205. The other one of the two output shafts 1 13 extends through the hollow shaft 203 and is supported by a bearing 206. The output shafts 1 13 may be provided with female splines for receiving male splines of stub axles 207 providing connection to a respective universal joint 1 15.

The subframe 106 of Figs. 2 to 7 defines a hole 401 (which may be best seen in Figs. 4 and 5) in which a part of the drive mechanism 104 resides. The drive assembly 101 of Figs. 2 to 7 comprises a container 301 located within the hole 401 . The container 301 contains at least a part of the drive mechanism 104. The drive assembly 101 also comprises a removable cover 208 that is attached to the subframe 106 and which covers a part of the drive mechanism 104. The removable cover 208 has edges that are configured to extend alongside edges of the container 301 . A seal 501 is provided between the edges of the removable cover 208 and the container 301 to enable containment of lubricant by the removable cover 208 and container 301 in combination.

It should be noted that, in the present example, the hole 401 extends through the continuous component 1 10 of the subframe 106 from an upper surface 304 to a lower surface 305 (shown in Fig. 3). Thus, in the present example, the container 301 is able to extend through the continuous component 1 10 of the subframe 106 and beyond the lower surface 305.

In the example of Figs. 2 to 7 the container 301 and removable cover 208 are similarly shaped shells which each extend approximately half way around the drive mechanism 104 and which have flanges 210 and 21 1 respectively (shown in Fig. 5), to enable connection of the removable cover 208 to the container 301 and also enable attachment of the removable cover 208 and container 301 to the subframe 106. The removable cover 208 and container 301 are attached to the subframe 106 with fasteners 212. The fasteners 212 may comprise bolts which extend through holes in the flanges 210 and 21 1 of the removable cover 208 and container 301 and into threaded holes provided in the subframe 106.

The seal 501 may comprise a bead seal that is located in a groove formed in the flanges 210 provided on the removable cover 208 and/or in the flanges 21 1 provided on the container 301 . As shown in Fig. 5, a second bead seal 501 A may be provided parallel to bead seal 501 with the fastening members 212 located between the two bead seals 501 , 501 A.

The container 301 and the removable cover 208 each define a portion of a first opening 302 and a portion of a second opening 303 (shown in Fig. 3) that are provided to allow access to respective ones of the output shafts 1 13. Radial shaft seals 209 are also provided between the removable cover 208 and container 301 within the openings 302 and 303 to maintain lubricant within the container 301 and removable cover 208. The radial shaft seals 209 have an outer cylindrical surface arranged to provide a seal with the removable cover 208 and container 301 and a bore arranged to provide a seal with a respective stub axle 207 connected to the output shafts 1 13.

The removable cover 208 and the container 301 may be formed of a plastics material or alternatively may be formed of a metal. If the removable cover 208 and/or container 301 are formed of a plastics material, portions of the removable cover 208 and/or container 301 may be reinforced with a metallic structure about which the plastics material is moulded. Specifically, if the removable cover 208 is formed of a plastic material, portions of the removable cover 208 around the location of the bearings 205 and 206 and extending along the flanges 210 to the locations of the fasteners 212 may be reinforced with a metallic structure 601 , as shown in the cross-section of Fig. 6. Similarly, if the container 301 is formed of a plastics material, portions of the container 301 around the location of the bearings 205 and 206 and extending along the flanges 21 1 may be reinforced with a metallic structure 602.

Fig. 6 also shows one of two C-shaped bearing surfaces 603, defined by the continuous component 1 10 of the subframe 106, which are provided to support the container 301 at the positions of the bearings 205, 206. Thus, it will be understood that the continuous component 1 10 transmits loads between the bearings 205, 206 and the mounting features 107 and 108. Separate fasteners 213, such as bolts, rivets or clips, may be provided for fastening the removable cover 208 to the container 301 before the removable cover 208 and container 301 are positioned on the subframe 106. Consequently, the drive mechanism 104 located within the container 310 and removable cover 208, the bearings 205, 206, which support the output shafts 1 13, and the radial shaft seals 209 may be formed as a module. Consequently the module may be installed as a single unit on the subframe 106 by positioning the container 301 in the hole 401 formed in the subframe 106 and fixing the removable cover 208 and container 301 to the subframe 106 with fasteners 212. Stub axles 207 with male splines may then be located through the radial shaft seals 209 and fitted into the female splines provided in the output shafts 1 13. Cables (not shown) may be positioned through an aperture in the removable cover 208 or container 301 that provide electrical connection to the coils of the stator 201 . Alternatively, the removable cover 208 or container 301 may be provided with an impervious electrical connector connected to the stator 201 and enabling electrical connection to external electrical wiring.

An alternative example of the drive assembly 101 of Fig. 1 is shown in the top view of Fig. 8, cross-sectional side view of Fig. 9 and a second cross-sectional view in Fig. 10, identified as D in Fig. 8. The features of the drive assembly 101 of Figs. 8 to 10 are generally the same as those of Figs. 2 to 7 and they have been labelled using the same reference signs.

The drive assembly 101 of Figs. 8 to 10 differs from the drive assembly 101 of Figs. 2 to 7 as follows. Firstly, instead of a hole 401 , the subframe 106A of Figs. 8 to 10 is provided with a recess 901 (shown in Fig. 9) in which the container 301 is located. Thus, a portion of the drive mechanism 104 including the electric motor 1 14 is located within the container 301 within the recess 901 . A portion 902 of the subframe that provides the recess 901 adds to the strength and rigidity of the subframe 106A, when compared with the subframe 106. In addition, it provides mechanical support to the container 301 , which may therefore be formed of thinner and lighter material. As previously mentioned, the container 301 may be formed of a plastics material.

The portion 902 of the subframe 106A in which the container 301 resides may be provided with one or more apertures 903 to reduce the weight of the subframe 106A. However, as in the example of Figs. 2 to 7, the container 301 in combination with the removable cover 208 is arranged to contain oil (not shown) that may be provided to lubricate the drive mechanism 104.

The drive assembly 101 of Figs. 8 to 10 also comprises a support 801 which extends over the removable cover 208. The support 801 may be formed of a stronger material than the removable cover 208, which again may be formed of a plastics material. For example, the support 801 may be formed of a metal, such as steel or aluminium alloy.

The support 801 may have flanges 802 (shown in Figs. 8 and 10) configured to extend over the length of the flanges 210 provided on the removable cover 208. The fasteners 212 may fix the flanges 802 of the support 801 to the subframe 106A and the flanges 210, 21 1 of the removable cover 208 and container 301 may, in this way, be clamped between subframe 106A and the flanges of the support 801 .

The support 801 may also have one or more other portions 803 that form a recess 904 (shown in Fig. 9) in which a central portion of the removable cover 208 resides. The support 801 may therefore provide support to the wall of the removable cover 208. In addition, the support 801 may also provide additional strength to the subframe 106A.

End portions 804 of the support 801 may extend around bearings 205 and 206 and therefore the bearings 205 and 206 may be more rigidly held with respect to the subframe 106A.

The support 801 may define one or more apertures 805 in order to reduce the weight of the support 801 . A second alternative example of the drive assembly 101 of Fig. 1 is shown in the top view of Fig. 1 1 ; a cross-sectional side view of Fig. 12; a second cross-sectional view in Fig. 13, which is identified as plane E in Fig. 1 1 ; and a third cross-sectional view in Fig. 14, which is identified as plane F in Fig. 1 1 . The features of the drive assembly 101 of Figs. 1 1 to 14 are generally the same as those of Figs. 2 to 7 and they have been labelled using the same reference signs.

The drive assembly 101 of Figs. 1 1 to 14 differs from the drive assembly 101 of Figs. 2 to 7 in that it does not include the container 301 . Instead, the subframe 106B of Fig. 1 1 to 14 defines a recess 1201 (shown in Figs. 12 and 13) in which the drive mechanism 104 is fitted directly. Thus, the stator 201 may be fixed to the subframe 106B in direct contact with the inner surface of the recess 1201 . The inner surface of the recess 1201 is continuous and therefore, in combination with the removable cover 208, the subframe 106 is arranged to provide a container for retaining a lubricant in which the drive mechanism 104 may be immersed. Bead seals 1301 (shown in Fig. 13) may be provided between the flanges 210 of the removable cover 208 and adjacent surfaces of the subframe 106B.

The subframe 106B and the removable cover 208 each define portions of 1 101 openings provided at each of two ends of the drive assembly 101 of Figs. 1 1 to 14, to allow access to the output shafts 1 13. The bearings 205, 206 are positioned between the subframe 106B and the removable cover 208 near to the openings 1 101 . The continuous component 1 10 of the subframe 106B defines C-shaped bearing surfaces 1203 (shown in Figs. 12 and 14) against which the bearings 205, 206 may be directly positioned.

Radial shaft seals 209 are also provided at the openings 1 101 . The radial shaft seals 209 have an inner surface for sealing with a stub axle 207 and outer surface that seals against the removable cover 208 and the subframe 106B.

In additional alternative embodiments, a drive assembly 101 as described with reference to Figs. 2 to 7 or Figs. 1 1 to 14 may be provided with a support 801 over the removable cover 208 like the support 801 of Figs. 8 to 10.

A flow-chart outlining a method 1500 of mounting a drive mechanism 104 is shown in Fig. 15. At block 1501 a drive mechanism 104 is positioned within a hole 401 or recess 901 , 1201 of a subframe 106, 106A, 106B, wherein the subframe 106, 106A, 106B has at least a first mounting feature 107 for mounting the drive assembly 101 at a first side of a body 102 of a vehicle 103 and at least a second mounting feature 108 for mounting the drive assembly 101 at a second side of the body 102 of the vehicle 103. Furthermore, the subframe 106, 106A, 106B comprises a continuous component 1 10, 1 10A extending from the first mounting feature 107 to the second mounting feature 108. For example, in the embodiments shown in Figs. 1 to 14 and 16 to 19, the subframe 106, 106A, 106B has a first two mounting features 107 for mounting the drive assembly 101 at a first side of a body 102 of a vehicle 103 and a second two mounting features 108 for mounting the drive assembly 101 at a second side of the body 102 of the vehicle 103; and the subframe 106, 106A, 106B comprises a continuous component 1 10, 1 10A extending from the first two mounting features 107 to the second two mounting features 108.

In the example of Figs. 2 to 7 and 8 to 10, the drive mechanism 104 may be pre-assembled within the container 301 with the removable cover 208 attached and with the bearings 205, 206 fitted to the output shafts 1 13. The radial shaft seals 209 may also be previously fitted within the openings (such as openings 302 and 303 of Fig. 3) formed at each end of the container 301 and removable cover 208 that provide access to the two output shafts 1 13. However, if the seals 209 are not already fitted, they may be pushed in axially before, or after, the process at block 1502. In the example of Figs. 1 1 to 14, the rotor 202 and stator 201 of the electric motor 1 14 are pre-assembled and connected to the gear and differential mechanism 204, and the bearings 205 and 206 are fitted to the output shafts 1 13. This assembly is then positioned on the subframe 106B at block 1501 of the method 1500, so that the stator 201 rests against the inner surface of the recess 1201 in the subframe 106B and the bearings 205, 206 are located within the C-shaped bearing surfaces 1203 of the subframe 106B. The removable cover 208 may then be fitted over the motor 1 14 and the gear and differential mechanism 204. When fitting the cover 208, cables from the stator 201 may be passed through an orifice in the removable cover 208.

At block 1502, the removable cover 208 is attached to the subframe 106, 106A or 106B so that the removable cover 208 covers at least a part of the drive assembly 104. In an example, the removable cover 208 may be formed of a plastics material and the flange 210 of the removable cover 208 may be reinforced with steel, and the process at block 1502 may comprise bolting the steel reinforced flange of the removable cover 208 to the subframe 106, 106A or 106B. Alternatively, a support 801 may be located over the removable cover 208 and the flange 210 of the removable cover 208 may be clamped between the support 801 and the subframe 106, 106A or 106B, for example by bolting the support 801 to the subframe 106, 106A or 106B.

If the radial shaft seals 209 are not already fitted, these may be fitted after the process at block 1502 by pushing the seals 209 axially into the openings 302, 303 or 1 101 . The stub axles 207 with male splines may then be inserted axially though the radial shaft seals 209 into female splines provided in the output shafts 1 13 of the drive mechanism 104.

A second vehicle 1603 comprising a rear-wheel-drive car is shown schematically in Fig. 16. The car 1603 comprises a drive assembly 101 A mounted on the body 1602 of the car 1603. The drive assembly 101 A comprises a drive mechanism 104A having two output shafts 1613 for connection to wheels 1605A of the car 1603. The drive mechanism 104A comprises a differential 1614 that has an input shaft 1651 driven by an engine 161 1 via a transmission 1612, a drive shaft 1652 and universal joints 1653 and 1654. The differential 1614 may be of a known type for driving the rear wheels of a vehicle.

In the present example, the engine 161 1 is mounted remotely from the drive mechanism

104A, the engine 161 1 being mounted in an engine compartment 1655 towards the front of the vehicle 1603 while the drive assembly 101 A is mounted towards the rear of the vehicle 1603.

The two rear wheels 1605A of the car 1603 are driven via halfshafts 1616 connected to the output shafts 1613 of the drive mechanism 104A via stub axles 1607 and universal joints 1615.

The drive assembly 101 A also comprises a subframe 106C having a first two mounting features 107 for mounting the drive assembly at a first side of the body 1602 of the vehicle 1603 and a second two mounting features 108 for mounting the drive assembly at a second side of the body 1602 of the vehicle 1603. The mounting features 107 and 108 may comprises holes for receiving bushings as described above with regard to the drive assembly 101 of Fig. 1 . A removable cover 208A is attached to the subframe 106C and covers at least a part of the drive mechanism 104A.

Like the previously described embodiments, the subframe 106C of drive assembly 101 A comprises a continuous component 1 10A extending from the first two mounting features 107 to the second two mounting features 108.

An example of the drive assembly 101 A is shown in the top view in Fig. 17, the cross- sectional side view in Fig. 18 and a second cross-sectional view in Fig. 19 through a plane "G" that is identified in Fig. 17.

In the example of Figs. 17 to 19 the drive mechanism 104A is located within a container 301 A (shown in Figs. 18 and 19) that has edges sealed against edges of the removable cover 208A. For example, the edges of the removable cover 208A and the container 301 A may be provided with flanges 21 OA and 21 1 A in a similar manner to those of the container 301 and removable cover 208 described above. A bead seal may be provided between the flanges 210A and 21 1 A to enable the container 301 A in combination with the removable cover 208A to contain oil for lubricating the differential 1614. The container 301 A and the removable cover 208A may be attached to the subframe 106C by fasteners 212, such as bolts, located though holes in the flanges 21 OA and 21 1 A, that engage threaded holes in the subframe 106C. The removable cover 208A and container 301 A differ from the removable cover 208 and container 301 of Figs. 2 to 7 in that they define a third opening to allow access to the input shaft 1651 as well as two openings for the output shafts 1613. Each of the three openings is provided with a radial shaft seal 209 that has an outer surface sealing against inner surfaces of the container 301 A and removable cover 208A. Two of the radial shaft seals 209 have an inner surface which seals against a stub axle 1607 fitted to the output shafts 1613 of the differential, and the third radial shaft seal 209 seals against a stub axle 1607A fitted to the input shaft 1651 .

Each of the output shafts 1613 and the input shaft 1651 is supported by a respective bearing 205, 206 and 1701 . The continuous component 1 1 OA of the subframe 106C defines C- shaped bearing surfaces 1901 (shown in Fig. 19) at the locations of the bearings 205, 206 and 1701 to provide support for the bearings and to allow loads from the bearings 205, 206 and 1701 to be transferred through the continuous component of the subframe 106C to the mounting features 107 and 108. The container 301 A and the removable cover 208A may be formed of a plastics material that is provided with steel reinforcement at the position of the bearings 205, 206 and 1701 and along the flanges 21 OA and 21 1 B to positions where the container 301 A and removable cover 208A are attached to the subframe 106C, for example by bolts.

In the present example, the container 301 A, and a lower portion of the differential 1614, is located within a hole 1801 in the continuous component 1 1 OA of the subframe 106C. However, it will be appreciated that, like the embodiment of Figs. 8 to 10, the container 301 A and a lower portion of the differential 1614 may be located within a recess formed in the continuous component 1 10A of the subframe 106C. Also like the embodiment of Figs. 1 1 to 14, the lower portion of the differential 1614 may be located within a recessed portion of the continuous component 1 10A of the subframe 106C and therefore the container 301 A may be omitted. In this case the removable cover 208A may be attached directly to the subframe 106 and seal against the subframe 106C.

It will also be appreciated that a metal support, similar to support 801 of Figs. 8 to 10 may be fitted over the removable cover 208A to provide support to the removable cover (which may be formed of a plastics material) and/or to provide additional strength to the subframe 106C. Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. For example, in an alternative embodiment the drive mechanism is located in a recess in the continuous component forming the subframe. The recess has a main opening to allow the drive mechanism to be installed within the recess. In this alternative embodiment, the subframe defines two additional openings which provide access to the output shaft and which contain the radial shaft seals, i.e. the radial shaft seals are completely surrounded by the subframe. Access to supporting surfaces for the bearings of the output shafts is provided via the main opening, and additional fixing elements are provided to fix the bearings in position on the bearing surfaces. In this embodiment, the removable cover is sealed against the subframe and does not seal against the radial shaft seals. Therefore, to assemble this alternative drive assembly, the drive mechanism with bearings fitted to the output shafts is passed through the main opening into the recess and the bearings are fixed in place on the bearing surfaces of the subframe. The cover is positioned over the main opening and fixed in place to seal it. The radial shaft seals are inserted into the additional openings in the subframe and then male splines of stub axles may be inserted through the radial shaft seals and into female splines in the output shaft. The subframes 106, 106A, 106B, 106C described above have a first two mounting features 107 for mounting the drive assembly 101 at a first side of the body 102 of the car 103 and a second two mounting features 108 for mounting the drive assembly 101 at a second side of the body 102. However, in alternative embodiments, the drive assembly 101 has a subframe that has a first single mounting feature 107 for mounting the drive assembly 101 at a first side of the body 102 of the car 103 and a second single mounting feature 108 for mounting the drive assembly 101 at a second side of the body 102. In such embodiments, the subframe may be provided with a third mounting feature arranged to be fixed to the body 102 of the car 103, either in front or behind the drive mechanism, so that the first mounting feature 107, the second mounting feature 108 and the third mounting feature define a triangle. In such embodiments, the third mounting feature may be positioned in the vicinity of a centerline of the body 102 and closer to the centerline than it is to either of the first or second mounting features. Typically, the third mounting feature is positioned on the centerline of the body 102. A further embodiment will now be described as shown in fig 20 which shows a bottom view of a drive assembly 1002. The drive assembly 1002 shown in Fig 20 has three mounting features 107, 108, 109.

The drive assembly 1002 has a subframe 106D that has a first single mounting feature 107 for mounting the drive assembly 1002 at a first side of the body 102 of the car 103, a second single mounting feature 108 for mounting the drive assembly 1002 at a second side of the body 102 and a third single mounting feature 109 mounted either fore or aft in the car 103 on a suitable body panel. The third single mounting feature 109 may be placed on the centerline of the vehicle 103 such that the geometry of the three mounts form a symmetrical triangle formation. Alternately the third single mounting feature 109 may be placed slightly off the centerline of the vehicle.

In an alternate embodiment where a mechanical driveshaft (not shown) may be provided as an input to the embodiment of fig 20, it may be necessary to position the third single mounting feature 109 in a position which would not clash with the mechanical driveshaft. The third single mounting feature 109 may be higher or lower in the vehicle to avoid a mechanical driveshaft (not shown) to suit package constraints.

Fig 21 shows a cross section taken at plane "H-H" shown in Fig.20. The subframe 106D provides a continuous component extending from the first mounting feature (107) to both the second mounting feature (108) and the third mounting feature (109). The subframe 106D has a recess formed into it which the container 301 may be located. As an example the container 301 seats into the subframe 106D recess and the removable cover 208B is secured in place over the drive mechanism 104 using the fixings 212A. As an example, the fixings 212A could bolt right through the removable cover 208B and the container 301 to screw into a female thread provided in the subframe 106D. In another example, the removable cover 208B and the container 301 could be secured together directly using local fixings. Subsequent fixing of the joined container 301 and removable cover 208B to the subframe 106D could be done with other conventional fixings (not shown) from above or below the subframe 106D.

The above-described drive assemblies 101 are generally arranged such that the drive mechanism 104, 104A is mounted above an upward facing surface of the respective subframe 106, 106A, 106B, 106C. However, in alternative embodiments, the drive mechanism (104, 104A) may be mounted below a downward facing surface of the respective subframe 106, 106A, 106B, 106C. Thus, for example, the drive mechanism 104, 104A might be detached and lowered from the subframe 106, 106A, 106B, 106C, while the subframe remains attached to the vehicle 103, 1603.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not. Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.