Toyota tests Tesla's product-development style

  • 10-Oct-2011 02:06 EDT
RAV4 EV crash test.jpg

A prototype-build of the RAV4 EV after the vehicle underwent a 35 mph (56 km/h) frontal barrier crash test at the Toyota Technical Center near Ann Arbor.

Bringing Toyota's first North American-developed EV to market in 2012 represents a new exercise for a team of engineers.

"This is a unique program, and it's being done in collaboration with another vehicle development organization," Greg Bernas, RAV4 EV's chief engineer, said during an AEI interview at the Toyota Technical Center (TTC) in York Township, MI.

Toyota's usual work practice for U.S.-developed vehicles involves several on-site meetings to address specific issues. In addition, regular reports outlining the direction U.S.-based technical specialists intend to pursue are relayed to officials at Toyota Motor Corp. in Japan for information sharing and/or final approval.

"This process takes time," Bernas said. But modifications to Toyota's standard work protocol have translated to shortened timelines at key points along the RAV4 EV's development schedule.

As one example, the EV's styling "was reduced to two months for the RAV4 EV because all decisions were made in North America," said Bernas, who also served as chief engineer for the Toyota Venza.

In addition to Tesla Motors supplying all EV-related components (including battery technology, drive unit, charger, and DC/DC components), the Palo Alto, CA-based OEM's nimble product process is leaving other imprints on the new battery-electric compact utility.

"We are utilizing some of Tesla's development methods for our prototype vehicle builds to quickly solve problems with a team of experts, so we can possibly get more iterations in a shorter period of time," said Bernas.

According to Camille Ricketts, Tesla Communications Manager, Tesla's product development approach means engineers, designers, and customer service teams "work so closely together."

Such interactions allow the upstart electric vehicle maker "to incorporate feedback quickly and efficiently to improve our products," she noted.

Future Tesla-to-Toyota transfers are possible. According to Bernas, in the coming months Toyota officials will determine if a more streamlined production process, similar to what is being used for the RAV4 EV, can be applied to other low-volume programs.

"For the RAV4 EV program, we wanted to mesh best practices to achieve Toyota quality with Tesla's entrepreneur-style attitude," he said.

Technical details and testing

The new battery-electric-powered compact SUV significantly differs from the first-generation, Japan-developed vehicle produced from MY1998 through MY03. That vehicle used NiMH battery chemistry.

The next-generation RAV4 EV uses a slightly modified RAV4 platform. Its Tesla-supplied electric powertrain is comprised of a Li-ion battery pack, an AC induction motor, a single-speed gearbox, and a drive inverter. The system is expected to provide a range of more than 100 miles (161 km) on a single charge.

The liquid-cooled battery pack is comprised of approximately 4000 cells arranged in series. The pack will be packaged underneath the vehicle where the exhaust and fuel tank are located on the gasoline-fueled RAV4.

"With the EV components, our main goal was to minimize the added weight by optimizing the new bracket designs and by using materials with less mass for mounting the EV components," explained Bernas.

The 35-unit demonstration/evaluation fleet is using a number of EV-related components that are shared with or very similar to those on the Tesla Roadster. But the production vehicle will share various EV-related components with the 2013 Tesla Model S, according to Bernas.

Hundreds of CAE simulations were conducted to develop the unique structures that surround the EV systems on the RAV4 EV. It is the first electrified vehicle ever crash-tested at TTC.

According to Scott Miller, General Manager of Vehicle Safety and Crashworthiness at the facility, "We typically require about 12 days to build, test, and post-test an ICE-powered vehicle. Currently, we are requiring 25 to 50% more time for each EV test."

As of September 2011, TTC technical specialists had conducted 37 full vehicle crash tests for front, side, and rear impacts, as well as internal modes targeting the battery pack.

"We'll likely have 40 more vehicle tests before the start of production next year," noted Miller.

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