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FEATURE


SPRINGS, SHOCK ABSORBERS & WIRE FORMS


RETAINING RING DESIGNS: MAKING THE CHOICE FOR ELECTRIC VEHICLES


WAVE SPRINGS OR


With electric vehicle (EV) adoption on the increase – almost a third of all cars in 2023 have been made fully electric or hybrid, according to


SMMT – a new set of challenges are emerging for automotive designers and manufacturers. Here Simon Ward, technical manager at TFC, looks into the use of wave spring and retaining ring designs for EVs


E


lectric vehicles are growing in popularity. In fact UK factories have turned out a record 234,066 battery electric (BEV), plug-in hybrid (PHEV) and hybrid (HEV) electric vehicles, with combined volumes up 4.5% year- on-year to represent almost a third (30.2%) of all car production. However, rapid EV market growth has created pressure on design teams to deliver innovation and maximise capacity, and created some new factors to consider.


MANAGING TIGHT SPACE CONSTRAINTS The difference in performance and size between an internal combustion engine (ICE) and an


44 DESIGN SOLUTIONS APRIL 2023


electric vehicle means that springs and other components must fight in tighter spaces. In applications where space is limited, a good option can be wave springs, a reliable alternative to coil springs that offer the same force as a traditional coil spring at reduced operating height. This decreases the spring cavity, and therefore the overall assembly size, making it ideal for EVs. Wave springs are available in a variety of


diameters, from 5mm upwards, making them suitable for a range of EV related applications. Of additional benefit, manufacturers can also alter the thickness, number of waves per turn, and the number of turns on their design.


For instance, if a light duty spring is needed, it can be designed with a thinner wire or fewer waves. For high force and precision, manufacturers can consider a nested wave spring with multiple turns. A good understanding of wave spring


performance will help designers make sure their product has longevity, while achieving performance improvements.


COPING WITH INCREASED ROTATIONAL REQUIREMENTS Drive systems for EVs frequently have much higher rotational capacity requirements than ICEs, and can be 15,000 revolutions per minute


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