Mazda has filed a patent for a tri-motor, all-wheel-drive, hybrid system, which is said to be destined for the next-generation Mazda MX-5 sports car (codenamed NE or NG), due in the coming years.
Filed in March 2019 – but not published online until December 2021 – the patent (uncovered by The Drive) depicts a hybrid system for a front-engined, rear-wheel-drive vehicle, with three electric motors, all-wheel drive, an automatic transmission, and a compact battery allowing a limited electric-only driving range.
While not confirmed for the MX-5, the patent filing says it aims to prevent “falling into the vicious cycle between enhancement of driving via the motor and an increase in vehicle weight” – making it a perfect fit for Mazda’s roadster, given its focus on driver engagement through keeping weight low.
The next-generation Mazda MX-5 – codenamed NE or NG, following prior NA to ND generations of MX-5, and the NF (or NE) tags given to the related Fiat/Abarth 124 Spider – is expected to launch by 2025, with many speculating mild-hybrid power will feature under the bonnet.
Underpinning the hybrid system described in the patent is a layout familiar to buyers of the current MX-5: an internal combustion engine under the bonnet, pictured with four cylinders, sending drive to the rear wheels.
However, the patents bolts in three electric motors: one 25kW ‘P1’ motor connected to the engine and transmission, and two ‘P4’ motors, each developing 17kW and mounted within the front wheel axles, enabling all-wheel drive.
The patents lists a combined maximum power output of 53kW from the trio of motors, achieved at 130km/h – adding which to the current ‘ND’ MX-5’s 135kW/205Nm 2.0-litre ‘SkyActiv-G’ petrol engine would make the ‘NE’ model the most powerful factory MX-5 ever produced.
Rumours suggest the next Mazda MX-5 may receive a version of the Mazda 3 hatch and CX-30 small SUV’s available 2.0-litre naturally-aspirated ‘SkyActiv-X’ engine, developing 132kW and 224Nm in Australian-market vehicles, with a 24-volt mild-hybrid system.
Electrical energy for the hybrid system is kept in a compact lithium-ion battery mounted in the vehicle’s floor, operating at 48 volts (more common to a mild-hybrid system), and offering 3.5kWh of storage – double or triple that offered by a Toyota Corolla or Camry Hybrid.
This electric power is routed to a capacitor placed in front of the engine, which is used to quickly supply and manage the power given to the front wheel motors – without repeatedly recharging and discharging the battery – while enabling regenerative braking under deceleration.
The engine’s power is sent to the rear wheels via a transaxle (combining the transmission, rear differential and axle into one unit) – but manual gearbox fans should look away, as the Mazda patent only makes reference to an automatic transmission.
The inclusion of an automatic gearbox allows the vehicle’s computers to use the electric motors to accelerate or decelerate the vehicle during downshifts and upshifts, to “suppress a stall … [or] … idling running feeling” and deliver seamless gear changes.
Advocating for its lightweight design, Mazda’s patent says that in vehicles with high-output electric motors, “a large capacity battery is necessary and the electrical system … needs to be electrically insulated sufficiently, [so] the overall weight of the vehicle increases and the fuel efficiency … reduces.”
While the patent filing doesn’t confirm a technology will reach showrooms, the patent makes reference to tuning the electric motors to meet the “travel condition requested in the WLTP [emissions regulations in Europe] test” – suggesting thought has been put into developing the system for a production car.
Mazda has confirmed the MX-5 will adopt hybrid or electric power by 2030, as part of the Japanese car maker’s broader electrification plans – though with the help of synthetic fuels, it could make the switch sooner.
“[Without speaking specifically] on MX-5 I think we’ve reached a level of comfort that, there’s work on batteries, there’s work on other things. We can improve the internal combustion engine with SkyActiv-X [petrol engine technology] and beyond, and Mazda’s working to do that,” Mazda Australia marketing boss Alastair Doak told Drive last week.
“If you can combine that kind of technology and that thinking with even some relatively lightweight form of electrification, then that means that car and that kind of ethos will continue for a long time to come.”
Keyword: New patent hints at tri-motor hybrid for next Mazda MX-5