Fly-By-Wire Steering

[vonk]

Does anybody have a link to a description of the '06 Prius' FBW steering, especially the steering assist actuator. TIA.

[Kain]

i haven't seen fly by wire it is electric yes but there is still a shaft running from the wheel to the rack and pinion...so it the assist actuator fails u can still steer. also the actuator is basically a 12v dc motor built into the steering gear of the rack...very simple.

[vonk]

Thanks for the response Kain. Seems rather straight forward. Now I wonder how they sense the torque in the steering column to regulate the motor. Strain gauges? Also, the 12 Volt motor must be geared somehow to produce the necessary assist torque. Do you know of a website where Prius/HiHy tech info or shop manuals can be accessed/downloaded?

Thanks

[Tideland Prius]

Yeah, it's conventional steering but with electric assist instead of hydraulic assist.

try techinfo.toyota.com

[vonk]

Thanks for the lead. Found exactly what I was looking for. Very cool. The concept is conventional but the packaging is very clever and compact. Toyota seems to really be into coaxial solution, what with the TSD and all. Hate to think what a new PS rack would cost.

[vonk]

PS: I first looked at the HiHy power steering, assuming that the Prius' was much the same. Not so. when I looked up the Prius system it turns out to be the same in principal only, but completely different in execution. Actually less compact than the HiHy.

[Tideland Prius]

oh really?

[vonk]

Yeah, the HiHy has the assist motor wrapped concentrically around the steering rack with a ball-and-groove reduction gear. The Prius has the assist motor behind the steering wheel, sticking off to the side from a conventional reduction gear. HiHy is probably a later design, introduced when it got hybrid.