Three-Dimensional Friction SHIM

Abstract

A shim for securing a battery frame assembly in a vehicle. The shim 100 comprises a substrate comprising a planar portion, having a main aperture 102 suitable for receiving a shaft of a fastener. A p

Description

TECHNICAL FIELD The present disclosure relates to a three-dimensional friction shim. Aspects of the invention relate to a shim, to a fastener assembly, and to a vehicle. BACKGROUND It is known to secure a battery frame to a vehicle structure using one or more bolted joints. Due to high local stiffness in both the battery frame and the vehicle structure, high shear loads are generated in bolted joints at the extremities of the battery frame assembly that attach the battery frame to the vehicle structure. Due to geometric limitations of a battery frame, it may not be practical to increase a number of bolted joints to share the shear load between more joints. Therefore, it is desirable to increase the shear force capacity of a bolted joint. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a shim, a fastener assembly, and a vehicle as claimed in the appended claims. According to an aspect of the present invention there is provided a shim for securing a battery frame assembly in a vehicle, the shim comprising a substrate having a main aperture suitable for receiving a shaft of a fastener; and a plurality of tabbed portions protruding from a planar portion of the substrate. The shim comprises a friction-enhancing coating. The friction-enhancing coating increases the coefficient of friction at the joint, causing less relative slip between the fastener and the spacer element. Due to reduced relative slip, the shear forces in the fastener are reduced. According to an aspect of the present invention there is provided a shim for securing a battery frame assembly in a vehicle, the shim comprising a substrate, the substrate comprising a planar portion, having a main aperture suitable for receiving a shaft of a fastener; and a plurality of tabbed portions protruding from the planar portion, wherein at least one of the tabbed portions is arranged to deform against a portion of a spacer element. The shim comprises a friction-enhancing coating. The friction-enhancing coating increases the coefficient of friction at the joint, causing less relative slip between the fastener and the spacer element. Due to reduced relative slip, the shear forces in the fastener are reduced. The use of tabbed portions, at least one of which deforms, enables the shim to be kept in place on the spacer element during assembling or disassembling of the joint between the fastener and the spacer element, because the friction shim remains affixed to the spacer element. This reduces a risk of errors in assembly of the spacer element assembly due to leaving out the friction shim. Securing the friction shim to the spacer element via the tabbed portions also improves manufacturability of the spacer element assembly. Optionally, the friction-enhancing coating is applied to both of a component facing surface of the planar portion of the shim and to a spacer element facing surface of the planar portion of the shim, whereby friction between the component and spacer element is enhanced when they are pressed against each other by a fastener. Optionally, the friction-enhancing coating comprises a nickel matric and embedded diamond particles. When the fixing is tightened into the spacer element, the planar portion of the friction shim is compressed between a surface of the fixing and a surface of the spacer element. The relative hardness of the diamond particles compared to the surfaces of the fixing and spacer element, causes the diamond particles to press into the surface of the fixing and / or spacer element. As such, a form fit is created between the friction-enhancing coating of the shim and the surface of the fixing and / or spacer element, which increases the coefficient of static friction between the shim and the surface of the fixing and / or spacer element. Optionally, at least one of the tabbed portions is elastically deformable. The tabbed portions may be elastically deformable or resiliently biased, such that the shim can be positioned overa portion of the spacer element and remain in position, due to the deformation of the tabbed portion(s) against the surface of the spacer element. As the friction shim is inserted over the portion spacer element, the tabbed portion(s) will be deformed by the force of the spacer element against the tabbed portion(s), however the elastic or resilient nature of the tabbed portions means that the tabbed portion will be biased back to its original shape, and thus will exert a force against the surface of the spacer element. The force exerted by the tabbed portion(s) against the spacer element acts to secure the friction shim in place on the spacer element. Optionally, at least one of the tabbed portions is arranged to engage with a recessed portion of the spacer element. Where the tabbed portion engages with a recessed portion of the spacer element, the interaction of the tabbed portion against a side surface of the recessed portion will prevent, or at least reduce the likelihood of, the friction shim being removed from the spacer element without force being applied to deform the tabbed portion(s) sufficiently to clear the side surface of the recessed portion of the spacer element. Accordingly, the friction shim is secured in place on the spacer element. Optionally, the substrate may comprise steel. A steel substrate has a strength sufficient to withstand the clamping force present in a bolted joint without yielding or compressing, in such a way that would otherwise cause loss ofclamping load. According to another aspect of the invention, there is provided a spacer assembly for a vehicle, comprising a spacer element comprising an aperture in a first surface; and a shim as described above, wherein the main aperture of the shim is arranged proximate the aperture of the spacer element, and wherein the tabbed portions is arranged to deform against a second surface of the spacer element. By using the friction shim in the joint between a component and the spacer element, the coefficient of friction between the component and spacer at the bolted joint is increased, and therefore the shear forces experienced by the fastener joining the component and spacer element are reduced. According to yet another aspect of the invention, there is provided a vehicle comprising a spacer assembly as described above. According to yet another aspect of the invention, there is provided a method of installing a component on a spacer element in a vehicle and using a shim as described above, comprising positioning the main aperture of the shim proximate an aperture of a spacer element; assembling the component on the spacer element; inserting a shaft of a fastener through the main aperture of the shim, an aperture of the component and the aperture of the spacer element; and tightening a portion of the fastener to press the shim between the component and spacer element. 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 anyway 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: Figure 1 shows a spacer assembly comprising a shim according to embodiments of the invention; Figure 2A shows a first view of a friction shim according to embodiments of the invention; Figure 2B shows a second view of the friction shim in Figure 2A; Figure 3 shows a tabbed portion of the friction shim ; Figure 4 shows an alternative spacer assembly comprising a shim according to embodiments of the invention; Figure 5 shows a view of an engagement between a spacer element and shim of the spacer assembly of Figure 4; Figure 6A and 6B show a first and second view respectively of an alternative friction shim according to embodiments of the invention; Figure 7 shows a vehicle; and Figure 8 shoes a flow chart showing a method of installing a shim according to embodiments of the invention. DETAILED DESCRIPTION With reference to Figure 1 there is shown a spacer assembly 10 suitable for securing a battery assembly of a vehicle. As shown in Figure 7, the spacer assembly may be installed in a vehicle 700. The spacer assembly 10 as illustrated in Figure 1 comprises a friction shim 100. The friction shim 100 comprises a substrate which itself comprises a planar portion having a main aperture 102. The main aperture 102 is suitable for receiving at least part of a shaft of a fastener. The substrate of the friction shim 100 further comprises one or more tabbed portions 204, the one or more tabbed portions 204 protruding from the planar potion of the friction shim 100. The tabbed portions 204 are arranged so as to deform against a surface of a spacer element 110. The tabbed portions 204 are functional to secure the friction shim 100 against a surface of the spacer element 110. The spacer element 110 comprises an aperture, wherein the main aperture 102 of the friction shim 100 is arranged so as to be positioned proximate the aperture of the spacer element 110 when the friction shim 100 is installed on the spacer element 110. Due to the geometry of the spacer element 110, the friction shim 100 cannot be retained against the spacer element 110 using a fixing such as a bolt or screw, and therefore the geometry of the tabbed portions 204 of the friction shim 100 function to provide the necessary force against the spacer element 110 to retain the friction shim 100 against the spacer element 110. The friction shim 100 comprises a friction-enhancing coating. The friction enhancing coating may increase the coefficient of friction on a surface of the friction shim 100 compared to the coefficient of friction for an uncoated surface of the friction shim 100. The friction-enhancing coating is applied over the substrate. The substrate may comprise steel. The substrate may comprise a steel foil. The substrate may comprise a carbon steel. The substrate may comprise one of C60 steel or C75 steel. The friction-enhancing coating may comprise a nickel matrix. The nickel matrix may have a thickness from 5 pm to 30 pm. In some embodiments the nickel matrix may have a thickness of 5 pm to 9 pm. In some embodiments the nickel matrix may have a thickness of 13 pm to 17 pm. In some embodiments the nickel matrix may have a thickness of 14 pm to 22 pm. In some embodiments the nickel matrix may have a thickness of 22 pm to 30 pm. The nickel matrix may comprise nickel-phosphorous. The friction-enhancing coating may comprise diamond particles embedded in the nickel matrix. The frictionenhancing coating may comprise an electroless nickel matrix in which a quantity of diamond particles is embedded. A mean particle size of the diamond particles on the surface of the shim may be 10 pm to 55 pm. The average concentration of diamond particles on the surface may be 8% to 60%. In some embodiments, the mean particle size is 10 pm and the average concentration of diamond particles may be 8% to 16%. In some embodiments, the mean particle size is 25 pm and the average concentration of diamond particles may be 8% to 25%. In some embodiments, the mean particle size is 35 pm and the average concentration of diamond particles may be 10% to 30%. In some embodiments, the mean particle size is 55 pm and the average concentration of diamond particles may be 20% to 60%. The friction shim 100 (i.e. the substrate of the friction shim 100) may have a thickness of 0.11 mm to 0.28 mm. In some embodiments, the thickness of the friction shim 100 may be 0.13 mm to 0.23 mm. In some embodiments, the thickness of the friction shim 100 may be 0.13 mm. In some embodiments, the thickness of the friction shim 100 may be 0.16 mm. In some embodiments, the thickness of the friction shim 100 may be 0.19 mm. In some embodiments, the thickness of the friction shim 100 may be 0.23 mm. In embodiments, the shim 100 may be formed as a single part. In embodiments, the substrate of the friction shim 100 may be formed using a laser cutting process. In embodiments, the substrate of the friction shim 100 may be formed using a stamping process. In some embodiments, the friction-enhancing coating may be applied to the substrate via a dipping process. In embodiments, the friction-enhancing coating may be applied to the substrate via a spraying process. Figures 2A and 2B show first and second views of the friction shim 100 employed in the assembly shown in Figure 1. The friction shim 100 comprises a planar portion having a main aperture 202. The main aperture 202 is sized suitably to receive at least part of a shaft of a fixing. The main aperture 202 is arranged so as to be positioned proximate an aperture of a spacer element when the friction shim 200 is inserted over a portion of said spacer element. The friction shim 200 comprises a plurality of tabbed portions 204a, 204b. The tabbed portions 204a, 204b, 204c protrude from the planar portion of the friction shim 200. In embodiments, the tabbed portions 204a, 204b may be arranged around a circumference of the planar portion of the friction shim 100. One or more of the tabbed portions 204a, 204b may be arranged so as to deform when the friction shim 100 is inserted over a spacer element. The tabbed portions 204a, 204b may be operable to secure the friction shim 100 against a surface of a spacer element, due to the force exerted by the deformation of the tabbed portions 204a, 204b against a surface of the spacer element. In embodiments, one or more of the tabbed portions 204a, 204b may be resiliently biased or elastically deformable, such that the tabbed portions 204a, 204b are biased toward their original shape or position. The tabbed portions 204a, 204b, 204c may extend / protrude substantially perpendicularly from the surface of the planar portion of the friction shim 200. The friction shim 100 comprises a friction-enhancing coating, as described previously herein. Figure 3 shows a tabbed portion 204 of the friction shim 100. The tabbed portion 204 extends perpendicularly from a surface 308 of the planar portion of the friction shim 100. The tabbed portion 204 may comprise a secondary tab 306, the secondary tab 306 protruding from a surface of the tabbed portion 204 in a direction toward a main aperture of the friction shim 100. In use, the secondary tab 306 may be arranged so as to abut a surface of the spacer element 110 in such a way that the contact of the secondary tab 306 with the spacer element exerts a force against said spacer element. The secondary tab 306 may be operable to deform against said surface of the spacer element. The tabbed portion 204 may be formed by bending a portion of the friction shim 100 such that the tabbed portion 204 protrudes substantially perpendicularly from the planar surface of the friction shim 100. The secondary tab 306 may be formed by bending a portion of the tabbed portion 204 such that the secondary tab 306 protrudes from a surface of the tabbed portion 204. Figure 4 shows an alternative spacer assembly 40 suitable for securing a battery assembly of a vehicle. The spacer assembly 40 as illustrated in Figure 4 comprises a friction shim 400. The friction shim 400 comprises a planar portion having a main aperture 402. The main aperture 402 is suitable for receiving at least part of a shaft of a fastener. The friction shim 400 further comprises one or more tabbed portions 504, the one or more tabbed portions 504 protruding from the planar portion of the friction shim 400. The tabbed portions 504 are arranged so as to engage with a recessed portion 412 of a spacer element 410. The tabbed portions 504 are functional to secure the friction shim 400 against a surface of the spacer element 410. The spacer element 410 comprises an aperture, wherein the main aperture 402 of the friction shim 400 is arranged so as to be positioned proximate the aperture of the spacer element 410 when the friction shim 400 is installed on the spacer element 410 by engaging the tabbed portions 404 of the friction shim 400 with the recessed portion 412 of the spacer element 410. Figure 5 shows a view 50 of an engagement between the spacer element 410 and the friction shim 400. The friction shim 400 comprises a plurality of tabbed portions 504a, 504b, 506. One or more of the tabbed portions 504a, 504b are deformable, such that the tabbed portion 504a, 504b can engage with a recessed portion 512 of the spacer element 410. One or more of the tabbed portions 506 may be rigid, such that they do not deform against a surface of the spacer element 510. The rigid tabbed portions 506 may be arranged such that alignment of the main aperture of the friction shim 500 and the aperture of the spacer element 510 is maintained. Additionally or alternatively, the rigid tabbed portions 506 may be arranged such that an opposing force is provided by the rigid tabbed portion 506 against a force exerted by the deformation of one or more of the deformable tabbed portions 504a, 504b. Figures 6A and 6B show first and second views of an alternative friction shim 600. The friction shim 600 comprises a planar portion having a main aperture 602. The friction shim 600 comprises a plurality of deformable tabbed portions 604a, 604b, 604c, 604d. The friction shim 600 comprises a plurality of rigid tabbed portions 606a, 606b, 606c, 606d. The deformable tabbed portions 604a, 604b, 604c, 604d and the rigid tabbed portions 606a, 606b, protrude from the planar portion of the friction shim 600. In embodiments, the deformable tabbed portions 604a, 604b, 604c, 604d and the rigid tabbed portions 606a, 606b, 606c, 606d may be arranged around a circumference of the planar portion of the friction shim 600. The deformable tabbed portions 604a, 604b, 604c, 606d may be arranged so as to deform when the friction shim 600 is inserted over a spacer element. In embodiments the deformable tabbed portions 604a, 604b, 604c, 606d may be arranged so as to engage with a recessed portion of a spacer element as in Figure 5. The deformable tabbed portions 604a, 604b, 604c, 604d may be operable to secure the friction shim 600 against a surface of the spacer element, due to the interaction of the deformable tabbed portions 604a, 604b, 604c, 604d and the recessed portion of the spacer element. In embodiments, the deformable tabbed portions 604a, 604b, 604c, 604d may resiliently biased or elastically deformable, such that the deformable tabbed portions 604a, 604b, 604c, 604d are biased toward their original shape or position. The rigid tabbed portions 606a, 606b, 606c, 606d may be arranged such that alignment of the main aperture 602 of the friction shim 600 and the aperture of a spacer element is maintained. Additionally or alternatively, the rigid tabbed portions 606a, 606b, 606c, 606d may be arranged such that an opposing force is provided by the rigid tabbed portion 606a, 606b against a force exerted by the deformation of one or more of the deformable tabbed portions 604a, 604b, 604c, 604d. The friction shim 600 comprises a friction-enhancing coating, as described previously herein. Figure 7 shows a vehicle 700 in accordance with an embodiment of the invention. A spacer element comprising one or more friction shims as described herein may be directly installed to the vehicle 700, or pre-attached to a sub-assembly which is then fitted to the vehicle 700. Figure 8 shoes a flow chart showing a method 800 of installing a friction shim such as those described above. At step 810, the shim is positioned such that a main aperture of the shim is arranged proximate an aperture of a spacer element. At step 820, a component is positioned on the shim and a shaft of a fastener is inserted through the component, the main aperture of the shim and the aperture of the spacer element. At step 830, 5 the fastener is tightened, such that a surface of the shim is compressed between a surface of the fastener and a surface of the spacer element. The fastener may be a screwthreaded bolt received in a correspondingly screw threaded bore of either the component or the spacer element. It will be appreciated that various changes and modifications can be made to the present invention without 10 departing from the scope of the present application.

Claims

1. A shim for securing a battery frame assembly in a vehicle, the shim comprising:a substrate, the substrate comprising:a planar portion, having a main aperture suitable for receiving a shaft of a fastener; anda plurality of tabbed portions (204) protruding from the planar portion, wherein at least one of the tabbed portions (204) is arranged to deform against a portion of a spacer element to retain the shim on the spacer element with the main aperture being aligned with a fastener-receiving aperture of the spacer element; anda friction-enhancing coating on at least the planar portion.

2. The shim of claim 1, wherein the friction-enhancing coating comprises a nickel matrix and embedded diamond particles.

3. The shim of claim 1 or 2, wherein the friction-enhancing coating is applied to both of a componentfacing surface of the planar portion of the shim and a spacer element-facing surface of the planar portion of the shim.

4. The shim of claim 1 or 2, wherein at least one of the tabbed portions (204) is elastically deformable.

5. The shim of claim 3, wherein at least one of the tabbed portions (204) is arranged to engage with arecessed portion of the spacer element.

6. The shim of any of claims 1 to 4, wherein the substrate comprises steel.

7. A spacer assembly for a vehicle, comprising:a spacer element comprising said fastener-receiving aperture in a first surface; andthe shim of any of claims 1 to 5, wherein the main aperture of the shim is arranged proximate the aperture of the spacer element, and wherein at least one of the tabbed portions (204) is arranged to deform against a second surface of the spacer element and retain the shim on the spacer element.

8. A vehicle comprising the spacer assembly of claim 6.

9. The vehicle of claim 8, when dependent on claim 3, wherein a component of the vehicle is mounted on the spacer assembly, wherein the component abuts the component-facing surface of the shim and the spacer element of the spacer assembly abuts the spacer element-facing surface of the shim, and wherein a fastener passes through the main aperture of the planar portion of the shim and clamps the shim between the component and spacer element.

10. A method of installing a component of a vehicle to a spacer element employing the shim of any of claims 1 to 6, comprising:positioning the main aperture of the shim proximate the aperture of the spacer element;retaining the shim on the spacer element by engaging said tabbed portions with the portion of the spacer element;positioning the component on the spacer element;5 inserting a shaft of a fastener through an aperture of the component, through the main apertureof the shim and through the aperture of the spacer element; andtightening the fastener to clamp the shim between the component and spacer element.

11. The method of claim 10, wherein the fastener is a screw-threaded bolt that that is screwed into a10 correspondingly screw threaded aperture of one of the component or spacer element.10

Images