Shaft assembly

Abstract

A vehicle axle shaft assembly includes a shaft (102, fig 1), a dustshield 112 and an annular seal 114. The shaft 102 includes a first end 104 and an opposing second end 106 with an outer mating surface 108 to transmit rotation from a driven member 110. The dustshield 112 extends from the first end 104 and rotates with it, and surrounds part of the shaft 102. The annular seal 114 is mounted on an inner surface 116 of the dustshield 112 and extends to define a gap 118 between the annular seal 114 and the first end 104, the gap 118 sealingly receiving an end of the driven member 110. The seal 114 prevents ingress of debris and / or egress of lubricant.

Description

TECHNICAL FIELD The present disclosure relates to a shaft assembly. Aspects of the invention relate to a shaft assembly for a vehicle, an axle assembly for a vehicle and a vehicle. BACKGROUND It is known to provide mating connections between a driven member, for example a drive gear or a drive collar, and a shaft. Such connections may be provided, for example, between an output of an electronic drive unit of an electric vehicle and a drive shaft. The driven member may have, for example, an inner mating surface, that is configured to cooperate with an outer mating surface of the shaft so that rotary motion may be transmitted to and / or from the driven member. To ensure rotation of the shaft, there is a close tolerance between the driven member and the shaft. The mating surfaces may be lubricated in order to protect the components from corrosion and / or wear. A dustshield, also known as a flinger, may be provided at the end ofthe shaft to restrict the ingress of environmental contaminants to the mating surfaces. It would be desirable to prevent the ingress of contaminants to, and the egress of lubricant from, the mating surfaces without increasing the complexity of the shaft components, thereby allowing manufacturers to leverage their existing production infrastructure, supply chains and manufacturing processes. It is an aim ofthe present invention to address one or more ofthe disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a shaft assembly, an axle assembly and a vehicle as claimed in the appended claims. According to an aspect ofthe invention there is provided a shaft assembly for a vehicle. The shaft assembly may include a shaft and a dustshield. The shaft assembly may also include a seal. In an embodiment, the shaft includes a first end and an opposing second end. The opposing second end of the shaft may include an outer mating surface. The outer mating surface may, for example, be configured to transmit rotary motion to and / or from a driven member, in use. In an embodiment, the dustshield extends from a first end ofthe shaft, for example the first end ofthe shaft. The dustshield may be configured to rotate with the shaft. Additionally or alternatively, the dustshield may be configured to at least partially surround the shaft. In an embodiment, the seal is an annular seal. The seal, for example the annular seal, may be mounted on an inner surface ofthe dustshield. The seal, for example the annular seal, may be configured to extend an inner surface, for example the inner surface, ofthe dustshield. A gap may be defined between the seal, for example the annular seal, and a first end, for example the first end ofthe shaft. The gap may be for, in use, sealingly receiving an end of the driven member. The seal may, therefore, prevent ingress of debris toward an outer mating surface of the shaft, for example the outer mating surface of the shaft. The seal may also prevent egress of lubricant from the outer mating surface of the shaft. According to another aspect of the invention there is provided a shaft assembly for a vehicle, the shaft assembly including a shaft, the shaft including a first end and an opposing second end, wherein the opposing second end of the shaft includes an outer mating surface that is configured to, in use, transmit rotary motion to or from a driven member, a dustshield extending from the first end of the shaft, wherein the dustshield is configured to rotate with the shaft and at least partially surround the shaft, and an annular seal, wherein the annular seal is mounted on an inner surface of the dustshield and is configured to extend therefrom so as to define a gap between the annular seal and the first end of the shaft, said gap for, in use, sealingly receiving an end of the driven member. The annular seal may, therefore, prevent ingress of debris toward an outer mating surface of the shaft, for example the outer mating surface of the shaft. The seal may also prevent egress of lubricant from the outer mating surface of the shaft. Advantageously the invention enables the provision of a shaft assembly and a seal as a single unit. In use, the seal is positioned radially outward of the driven member and is accommodated within the space provided by the dustshield. This means that there is no need to change the shape and / or configuration of the components of the driven member and / or other components of the drive line to accommodate the seal. In an embodiment, the shaft assembly also includes a driven member. Advantageously this enables the provision of a shaft assembly and a seal with the driven member as a single unit. In an embodiment, the inner surface of the dustshield includes a seal retaining feature. The seal retaining feature advantageously enables the annular seal to be held in position within the dustshield. The annular seal may be, for example, press fit to the inner surface of the dustshield. This removes the need for other components to ‘fix’ the annular seal in position. By mounting the annular seal on the inner surface of the dustshield, the dustshield provides some protection against damage to the annular seal, which might be caused by contaminants etc. In an embodiment, the seal retaining feature includes a first seal retaining portion and a second seal retaining portion. The first seal retaining portion may be configured to abut a first surface of the annular seal. The second seal retaining portion may be configured to abut a second surface of the annular seal. The abutting relation between the first and second seal retaining portions with the first and second surfaces of the annular seal beneficially enables the annular seal to be press fit into the seal retaining feature. In other words, the annular seal is held in the seal retaining feature of the dustshield by a friction or interference fit. The first seal retaining portion may be perpendicular to the second seal retaining portion. The first seal retaining portion may be, for example, oriented at an angle of approximately 90 degrees relative to the orientation of the second seal retaining portion. In other words the first seal retaining portion may have a surface which extends in a first direction and the second seal retaining portion may have a surface which extends in a second direction, wherein an angle of approximately 90 degrees is formed between the surface of the first seal retaining portion and the surface of the second seal retaining portion. The perpendicular arrangement of the first seal retaining portion and the second seal retaining portion beneficially enables the annular seal to be press fit into the seal retaining feature. The seal retaining feature may include a recess. The recess may, for example, facilitate the mounting of the annular seal to the inner surface of the dustshield. The annular seal may be statically mounted to the dustshield. The static mounting of the annular seal minimises or prevents energy loss. In one embodiment, for example, the annular seal may be bonded or adhered on the inner surface of the dustshield. The annular seal may be, for example, bonded or adhered to the seal retaining feature of the inner surface of the dustshield. In another embodiment, the annular seal may be injection moulded with the dustshield, for example injection moulded to the inner surface, e.g. a seal retaining feature on the inner surface, of the dustshield. In an embodiment, the dustshield has a frustoconical outer wall, for example a frustoconical outer wall that extends around the shaft. The frustoconical outer wall may include circumferential step portion. The step portion beneficially allows other components, for example other components of the drive line, to be occupied within the shaft assembly. This enables efficient packing of components within the space envelope. The frustoconical outer wall of the dustshield helps to ‘fling’ dirt and other contaminants away from the shaft as the dustshield rotates with the shaft. The inner space provided by the frustoconical outer wall accommodates other components, enabling efficient packing of components within the space envelope. The dustshield may be integral with the first end of the shaft. Alternatively, the dustshield may be configured for push-fit engagement with the first end of the shaft. Advantageously, the dustshield is simple to manufacture and doesn’t require complex fixings or additional components. According to another aspect of the invention, there is provided an axle assembly for a vehicle. The axle assembly may include a shaft assembly according to the preceding aspects of the invention. According to a further aspect of the invention, there is provided a vehicle. The vehicle may include a shaft assembly or an axle assembly as described in relation to the preceding aspects of the invention. The vehicle may also include a drive unit including the driven member, the driven member having an inner mating surface that is configured to, in use, cooperate with the outer mating surface of the shaft to transmit rotary motion to and / or from the driven member, where the annular seal forms a seal between the shaft and the driven member. 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 partial view of an axle assembly including a shaft assembly in accordance with an embodiment of the invention; FIG. 2A shows the shaft assembly of FIG. 1; FIG. 2B shows a partial view of the shaft assembly of FIG.1; and FIG. 3 shows a vehicle in accordance with an embodiment of the invention. DETAILED DESCRIPTION A shaft assembly 100 in accordance with an embodiment of the present invention is described herein with reference to the accompanying FIG. 1, FIG. 2A and FIG. 2B. As shown in FIG. 3, the shaft assembly 100 is installed in a vehicle 300. Referring now to FIG. 1, there is an axle assembly 136. The axle assembly 136 includes a shaft assembly 100. The shaft assembly 100 has a first end 104 and an opposing second end 106. The opposing second end 106 includes an outer mating surface 108 that, as will be described further below, is configured to, in use, transmit rotary motion to and / or from a driven member 110, for example a driven member 110 of a drive unit 138. The shaft assembly 100 also includes a dustshield 112. The dustshield 112 extends from the first end 104 of the shaft 102 and, as will be described further below, is configured to rotate with the shaft 102. The dustshield 112 has a frustoconical outer wall 132 which extends around the shaft 102. In other words, the dustshield 112 at least partially surrounds the shaft 102. The shaft assembly 100 further includes an annular seal 114. The annular seal 114 is mounted on an inner surface 116 of the dustshield 112 and, as will be described further below, is configured to extend from the inner surface 116 of the dustshield 112, thereby forming a gap 118 between the annular seal 114 and the first end 104 of the shaft 102. In use, the gap 118 sealingly receives an end of the driven member 110. In embodiments of the invention, the driven member 110 forms part of the shaft assembly 100. The shaft assembly 100 and the driven member 110 may, for example, be assembled as a unit for installation into the axle assembly 136 of a vehicle 300. The components of the shaft assembly 100 will be described in more detail, with reference to FIG. 2A and FIG. 2B. The dustshield 112 has a frustoconical outer wall 132 that extends around the shaft 102. As shown in FIG. 2A, the frustoconical outer wall 132 includes three circumferential step portions 134. Each of the circumferential step portions 134 forms a recess 130 on the inner surface 116 of the dustshield 112. The circumferential step portions 134 beneficially allow other components, for example other components of the drive line, to be occupied within the shaft assembly 100. This enables efficient packing of components within the available space envelope. The inner surface 116 of the dustshield 112 includes a seal retaining feature 120 which may, for example, be co-located with or correspond to the recess 130. With particular reference to FIG. 2B, the seal retaining feature 120 includes a first seal retaining portion 122 and a second seal retaining portion 124. The first seal retaining portion 122 and the second seal retaining portion 124 are formed by the circumferential step portion 134 such that the first seal retaining portion 122 is perpendicularto the second seal retaining portion 124. The first seal retaining portion 122 may be, for example, oriented at an angle of approximately 90 degrees relative to the orientation of the second seal retaining portion 124. In other words the first seal retaining portion 122 may have a surface which extends in a first direction and the second seal retaining portion 124 may have a surface which extends in a second direction, wherein an angle of approximately 90 degrees is formed between the surface of the first seal retaining portion 122 and the surface of the second seal retaining portion 124. The annular seal 114 is statically mounted to the dustshield 112, such that it rotates with the dustshield 112, in use. The annular seal 114 has a first surface 126 and a second surface 128. The first surface 126 is perpendicular to the second surface 128 such that the annular seal 114 can be push fit into the seal retaining feature 120 of the dustshield 112. The first surface 126 of the annular seal 114 thus abuts the first seal retaining portion 122 of the dustshield 112. In a similar way, the second surface 128 of the annular seal 114 abuts the second seal retaining portion 124 of the dustshield 112. The annular seal 114 is secured in the seal retaining feature 120 or recess 130 of the dustshield 112 by a friction or interference fit. The seal retaining feature 120 advantageously enables the annular seal 114 to be held in position within the dustshield 112. The annular seal 114 may be, for example, press fit to the inner surface 116 of the dustshield 112. This removes the need for other components to ‘fix’ the annular seal 114 in position. By mounting the annular seal 114 on the inner surface 116 of the dustshield 112, the dustshield 112 provides some protection against damage to the annular seal 114, which might be caused by contaminants etc. The shaft assembly 100 is assembled as follows. The annular seal 114 is push fit into the seal retaining feature 120 of the inner surface 116 of the dustshield 112 so that the first surface 126 of the annular seal 114 abuts a first seal retaining portion 122 of the dustshield 112 and a second surface 128 of the annular seal 114 (which is perpendicular to the first surface 126 of the annular seal 114) abuts a second seal retaining portion 124 of the dustshield 112 (which is perpendicular to the first seal retaining portion 122 of the dustshield 112). The dustshield 112 is then push-fit onto the first end 104 of the shaft 102. Advantageously, the dustshield 112 is simple to manufacture and doesn’t require complex fixings or additional components. The opposing second end 106 of the shaft 102 is mounted within the driven member 110 such that the outer mating surface 108 of opposing second end 106 of the shaft 102 engages an inner mating surface 140 of the driven member 110. The annular seal 114 sealingly engages an outer wall of the driven member 110 such that the volume defined by the shaft 102 and the driven member 110 is sealed. In this way, the ingress of contaminants from outside the shaft assembly 100 and the egress of lubricant from within the shaft assembly 100 are prevented. The shaft assembly 100 forms part of an axle assembly 136 which may be installed on a vehicle 300, for example the vehicle 300 of FIG. 3. In an embodiment, a drive unit 138 of a vehicle 300 drives the driven member 110, causing it to rotate. By virtue of engagement between the inner mating surface 140 of the driven member 110 and the outer mating surface 108 of the shaft 102, rotation of the driven member 110 causes the shaft 102 and the dustshield 112 to rotate. Beneficially, the frustoconical outer wall 132 of the dustshield 112 helps to ‘fling’ dirt and other contaminants away from the shaft 102 as the dustshield 112 rotates with the shaft 102. The inner space provided by the frustoconical outer wall 132 accommodates other components of the drive line, enabling efficient packing of components within the space envelope. Rotation of the shaft 102 causes rotation of other components of an axle assembly 136 and thus, rotation of a wheel 302 of the vehicle 300. In this example, the inner mating surface 140 of the driven member 110 is configured to cooperate with the outer mating surface 108 of the shaft 102 to transmit rotary motion from the driven member 110 to the shaft 102. Advantageously the invention enables the provision of a shaft assembly 100 and annular seal 114 as a single unit. In use, the annular seal 114 is positioned radially outward ofthe driven member 110 and is accommodated within the space provided by the dustshield 112, which means that there is no need to change the shape and / or configuration of the components of the driven member 110 and / or other components of the drive line to accommodate the annular seal 114. It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope ofthe present application. In the embodiment described above, the dustshield 112 is push-fit onto the first end 104 ofthe shaft 102. In other embodiments ofthe invention, the dustshield 112 may be formed as an integral component ofthe shaft 102. The dustshield 112 and the shaft 102 may, for example, be machined from a single piece of material. In the embodiment described above, the frustocomcal outer wall 132 of the dustshield 112 includes three circumferential step portions 134. It will be appreciated that, in some embodiments of the invention, the frustoconical outer wall 132 may include any number of circumferential step portions 134. The frustoconical outer wall 132 may, for example, include one circumferential step portion 134. Alternatively, the frustoconical outer wall 132 may be provided without a circumferential step portion. In the embodiment described above, the annular seal 114 is push-fit into the seal retaining feature 120 of the dustshield 112 and held in place by a friction or interference fit. In other embodiments of the invention, the annular seal 114 may be bonded or adhered to the inner surface 116 of the dustshield 112. The annular seal 114 may, for example, be bonded or adhered to the seal retaining feature 120 or recess 130 of the inner surface 116 of the dustshield 112. In yet further examples of the invention, the annular seal 114 may be injection moulded with the dustshield 112. The annular seal 114 may, for example, be injection moulded to the inner surface 116, e.g. a seal retaining feature 120 or recess 130 on the inner surface 116 of the dustshield 112. In the embodiment described above, the inner mating surface 140 of the driven member 110 is configured to cooperate with the outer mating surface 108 of the shaft 102 to transmit rotary motion from the driven member 110 to the shaft 102. The inner mating surface 140 of the driven member 110 may also be configured to cooperate with the outer mating surface 108 of the shaft 102 to transmit rotary motion from the shaft 102 to the driven member 110.

Claims

1. A shaft assembly for a vehicle, the shaft assembly comprising:a shaft comprising a first end and an opposing second end, wherein the opposing second end of the shaft comprises an outer mating surface that is configured to, in use, transmit rotary motion to or from a driven member;a dustshield extending from the first end of the shaft, wherein the dustshield is configured to rotate with the shaft and at least partially surround the shaft; andan annular seal, wherein the annular seal is mounted on an inner surface of the dustshield and is configured to extend therefrom so as to define a gap between the annular seal and the first end of the shaft, said gap for, in use, sealingly receiving an end of the driven member.

2. The shaft assembly of claim 1, further comprising the driven member.

3. The shaft assembly of claim 1 or 2, wherein the inner surface of the dustshield comprises a sealretaining feature.

4. The shaft assembly of claim 3, wherein the seal retaining feature comprises a first seal retaining portion and a second seal retaining portion, and wherein the first seal retaining portion is configured to abut a first surface of the annular seal and the second seal retaining portion is configured to abut a second surface of the annular seal.

5. The shaft assembly of claim 4, wherein the first seal retaining portion is perpendicular to the second seal retaining portion.

6. The shaft assembly of claim 4 or 5, wherein the seal retaining feature comprises a recess.

7. The shaft assembly of any one of claims 1 to 6, wherein the dustshield has a frustoconical outerwall that extends around the shaft.

8. The shaft assembly of claim 7, wherein the frustoconical outer wall includes a circumferential step portion.

9. The shaft assembly of any one of claims 1 to 8, wherein the annular seal is statically mounted to the dustshield.

10. The shaft assembly of any one of claims 1 to 9, wherein the dustshield is integral with the first end of the shaft.

11. The shaft assembly of any one of claims 1 to 9, wherein the dustshield is configured for push-fit engagement with the first end of the shaft.

12. An axle assembly for a vehicle, the axle assembly comprising a shaft assembly according to any one of claims 1 to 11.13, A vehicle comprising a shaft assembly according to any one of claims 1 to 11 or an axle assembly according to claim 12.

14. The vehicle of claim 13 comprising a drive unit comprising the driven member, the driven member having an inner mating surface that is configured to, in use, cooperate with the outer mating5 surface of the shaft to transmit rotary motion to or from the driven member, wherein the annularseal forms a seal between the shaft and the driven member.10

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