Mazda's hybrid timetable

Mazda will bring to market hybrid-drive models during 2013, and though the drive system will owe much to Toyota, each model will bear Mazda's own distinctive brand identity.

That's the plan in the short term, but the Hiroshima-based company is looking further ahead too. Eventually the company will bring its hybrid drivetrain systems development fully in-house. The question of when is one the company won't discuss, other than a comment from the company's head of R&D, Hirotaka Kanazawa. According to Kanazawa-san, 10 years to achieve this goal is too far in the future, but the company must develop hybrids, as a stepping stone to drivetrain technology beyond current combustion engines — what Mazda calls its 'building block strategy'. In the short term Mazda seems to be further along the hybrid development track than for battery-electric vehicles, but that's not to say the shortcomings of hybrids are necessarily easier to overcome.

"Hybrid has big cost issues as well," Kanazawa-san told motoring.com.au through an interpreter, the night before the Tokyo Motor Show's official opening. His answer explains why Mazda is buying in the technology from Toyota during the preliminary stage of development.

"Using Toyota's system we will [develop] some products, however not only that, we should develop Mazda's unique hybrid [system] as well."

Mazda's toehold in the world of hybrids is what might be described as a necessary evil, but the company has previously said it can incorporate hybrid-drive technology in Mazda models without reducing 'Zoom-Zoom' to 'Zzzzz-Zzzzz'.

"In today's environment, we think, rather than EVs or others, we should focus on [the] internal-combustion engine and we should enhance its efficiency — and we will provide better environmental performance... and we shouldn't forget about 'fun to drive' as well," Kanazawa-san said.

"Twenty years from now our 'Zoom-Zoom' car might be driven by [an electric] motor."

But the company won't be holding back development in the meantime.

"We can't wait so long," Kanazawa continued. "If we say we're going to introduce Mazda's unique hybrid 10 years later, it's too [late]."

Kanazawa-san can't see plug-in hybrids in Mazda's future while battery technology remains in its current state, but that's quite a qualifier.

"For the time being... there will be some improvements on the lithium-ion battery — and that will continue for some time. And of course, in the distant future, some new battery might appear. On the other hand, there are various research [efforts] on new types of fuel for internal-combustion engines. So EV will not totally replace internal-combustion engines... we need to think about the various types of internal combustion engine [types] as well."

Kanazawa-san said that Mazda was currently investigating "bio-mass" fuels for internal-combustion engines. After speaking with the R&D chief, motoring.com.au also heard from Mazda's General Manager of Powertrain Development, Mitsuo Hitomi. Hitomi-san is an abstract thinker who spoke — through an interpreter — on the proviso that the journalists present acknowledged that his comments were his own opinions and aspirations, not necessarily Mazda's corporate views.

Kicking off with the i-ELOOP system of capacitor-based regenerative braking, Hitomi-san claimed that capacitors had a wider role to play than just keeping the car's cabin nicely chilled or conserving energy for when the audio system is cranked up to 11.

"In Japan, many customers complain that those vehicles, which are said to have very good fuel economy do not provide very good fuel economy in the real world — including hybrids. But we believe that [with] the equipment of the i-ELOOP [the real world economy] would be significantly improved."

"When it comes to the vehicles, such as hybrids, which can have higher [energy storage capacity] in the battery, then that's fine — but when it comes to cheaper batteries, such as lead batteries, they need capacitors.

"Those cheap batteries cannot accept electricity — at the one time — in a massive [charge]. But when there is [heavy] deceleration, then there is a lot of power [to recover from braking]. Capacitors can store a massive volume of electricity and then the capacitor's [role] is to gradually transfer that energy to the batteries.

"Our ambition is to improve the engine efficiency [under] the lightest load conditions. My belief is that... we can operate the hybrid with a small motor and a small battery."

Hitomi-san explained at that point that such a hybrid-drive system would cost little to develop, but would remain highly fuel-efficient.

"Right now the lithium-ion battery and the large-size motor is mainstream in this industry, but if we have the very fuel-efficient hybrid with a small capacitor and small motor, we can be competitive enough with a fully-fledged hybrid."

Drawing graphs on the back of a napkin, Hitomi headed off into the realms of future technology speculation — but based on proven scientific principles. A freehand line illustrated an ideal 'efficiency' curve for a typical combustion engine. At lower revs, the efficiency falls off. The more torque available from lower rpm, the more efficient a combustion engine can be, but since the ideal is not practical in the real world (revs from 1500rpm down to idle, or lower), electric motors have to make up the difference, supplementing torque at engine speeds unfeasible for current technology combustion engines. Clutches and torque converters allow enough slip for the combustion engine to achieve a useful level of torque for reasonable efficiency.

"In the next step of SKYACTIV development, we are trying to realise the engine that has a curve like this," Hitomi continued, pointing to a shaded area of low engine revs on the graph where electric motors would typically operate efficiently, but combustion engines don't.

"I want to realise that in the near future, not the long-distance future."

SKYACTIV engines are already designed to stop and restart with individual pistons at top dead centre, waiting for a squirt of fuel and a spark for the engine to fire back into life. What Hitomi-san seems to be proposing for the next stage of development is an engine that will efficiently generate torque as it's cranking over from zero revs — much as electric motors do.

"If we come up with a super-efficient engine like this, then all the area [of the graph] where we need the assistance will be in this area only..." he explained, pointing to a smaller area of his hand-drawn graph.

With the combustion engine requiring a lower level of supplemental power from an electric motor, the electric motor could be smaller, the battery could be smaller (and therefore lighter), plus more electrical power for the motor could be stored in capacitors. In fact, Hitomi-san seemed to be of the opinion that a small electric motor might need no more than a conventional lead-acid battery and capacitors to propel the car forward from a standing start, supplementing the combustion engine at super-low speeds.

How would Mazda go about developing torquey and efficient combustion engines such as this? Hitomi-san mentioned bumping up the compression ratio of petrol engines as high as 20:1. While that seems extreme, the Mazda exec believes it's achievable by means of cancelling out uncontrolled detonation during a modified control phase.

"What we are aiming at is a completely different control phase, compared to the current engine, so we don't require high-octane gasoline. The current SKYACTIV [engine] requires... high-octane fuel.

"We have to find out the factors that [will] avoid knocking..."

According to Hitomi-san such an engine would run those very high compression ratios even on Australia's 91 RON fuel. In fact, lower octane fuels are potentially easier to handle. The compression ratio can be varied, potentially, through a more advanced direct-injection system not yet developed.

"This is only my vision," Hitomi-san said of the forecast for the new technology in Mazda's unique hybrid-drive system. "It's not Mazda's official vision yet..."

So the vision seems like something of an anti-climax, but that's not to say it's completely lacking. Earlier in the interview, Hitomi also said, apropos of high-torque engines capable of running down to very low revs: "That's my goal; it's not a dream..."

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