Relating to Tesla, consideration is often centered on its manufacturing struggles, the most recent actions of firm founder Elon Musk or, from a expertise perspective, its pure-electric powertrains. However with the Mannequin three, the agency can be aiming to pioneer a brand new strategy to chassis and suspension design.
Tesla’s strategy to designing these areas, that are essential parts in defining a automotive’s character and desirability, didn’t comply with typical automotive business observe for quantity automotive manufacturing. Autocar spoke completely with numerous Tesla engineers to realize an perception into that improvement course of.
Most producers lately construct main new fashions from a platform or structure, however when it got here to the design of the Mannequin three’s chassis and suspension, Tesla engineer caught with a ‘first ideas’ clean-sheet strategy. The place to begin have been the tyres, which Tesla describes because the unsung heroes of its vehicles and essential to really feel and drivability. Growth began in 2015 and Tesla labored with tyre producers for nearly three years, which is longer than the time spent on the Mannequin S’s tyres.
Tesla says tyres for a high-performance electrical car are challenged in a manner that these on a automotive powered by an inner combustion engine (ICE) should not. A two-wheel-drive Mannequin three with a long-range battery weighs simply over 1700kg, so tyres have to deal with excessive hundreds in addition to a 155mph prime velocity (for twin motor variations) plus continuous torque enter, both when accelerating or throughout regenerative braking.
The majority of mass of an EV is often positioned decrease than in an ICE-powered automotive because of the battery packs being mounted below the ground. Consequently, there’s much less vertical power build-up by the surface pair of tyres to generate grip once they nook. To deal with that, Tesla centered on tread stiffness, creating new compounds to ship the specified mixture of cornering grip and low rolling resistance. The tyres are stuffed with sound-absorbing foam to suppress noise amplified contained in the tyre cavity.
Every rear wheel has six levels of freedom – 5 hyperlinks and one damper, much like a double wishbone – however the hyperlinks have been break up to present higher management over the forces transmitted by the tyre’s contact patch. The entrance suspension has additionally been designed to supply most safety within the stringent, small-overlap frontal collision crash take a look at.
Aside from the direct damage that may happen in accidents, doorways can jam and EV batteries may be threatened too. To counter this, sacrificial hyperlinks are designed to snap when the entrance wheel and suspension takes a success.
That enables the wheel to rotate round a 3rd hyperlink, shifting the wheel outdoors of the physique and pushing the automotive, the occupants and the batteries away from the purpose of affect.
The extra motor in all-wheel-drive variants sits on two mounts within the ‘V’ of the entrance subframe and pivots backwards right into a void within the occasion of a collision. The electrical energy steering system has a fast 10:1 ratio, giving two turns lock-to-lock. The system has full redundancy with separate energy feeds taken immediately from the high-voltage battery, two digital management modules and two inverters offering ‘scorching backup’ if one fails.
Tesla’s engineering workforce opted to suit dearer four-pot brake calipers on the entrance of the Mannequin three quite than a less expensive, single-piston sliding model for superior pedal response. That additionally allowed the agency to design its personal piston seals that totally retract the brake pads after braking, chopping drag and boosting the out there driving vary.
The discs themselves have been designed to final for the lifetime of the automotive (about 150,000 miles), which is feasible as a result of the Mannequin three’s regenerative braking system reduces how a lot the traditional brakes are used. Rust may very well be a difficulty over that point, so engineers developed new anti-corrosion methods. Such consideration to element is indicative of the event workforce’s ‘extra and’ mantra: if an enchancment is made in a single space, whether or not for efficiency or value causes, Tesla’s workforce commits to creating one other enchancment elsewhere.
What’s the frequency, Elon?
Tesla drew on learnings from Nasa when refining the Mannequin three’s suspension settings to make sure the automotive can be snug.
The Californian firm’s engineers turned to a research by the area company on the boundaries of human functionality, which included analysis into how lengthy the physique may be subjected to a sure frequency with out feeling uncomfortable.
The vertical frequency (measured in hertz) at which the suspension strikes impacts not simply consolation however how a automotive feels to drive, whether or not it’s relaxed and serene or sharp and edgy.
Tesla says the suspension of most vehicles is sprung and damped to maneuver at between 1.0Hz and three.0Hz. For the Mannequin three, engineers settled on a vertical frequency for the suspension that’s equal of a brisk stroll or a gradual run to present a chassis really feel that was snug but sporty sufficient to harmonise with the efficiency of the powertrain.
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