| TRW has started production of
a hydraulic brake-by-wire system suitable for hybrids. The first application
is a full size premium SUV, available in the US at the end of 2007.
The slip control boost system (SCB) is designed for no brake-vacuum applications,
including those with regenerative braking, making it suitable for the
expanding hybrid vehicle market.
A high-pressure accumulator provides energy for the brake system, replacing
the vacuum boost of conventional systems – hybrids cannot provide
inlet manifold vacuum if operating in electric-only mode.
Greg Campau, senior braking engineering manager at TRW, said: “The
system performs the base braking, regenerative braking and all the traction
functions and replaces the booster, master cylinder and stability control.”
Development began in 2004. TRW is now ramping up to full production. The
firm is in discussions with several European OEMs for future applications
for MY2010 and beyond.
Lexus uses a similar system for the RX400h hybrid SUV. Porsche uses an
electric vacuum pump to power the brake servo of its new Cayenne hybrid
SUV.
“Our benchmarking of SCB shows our NVH is best-in-class. Vacuum
pumps aren’t as quiet as our hydraulic pump motor system,”
said Campau. |
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