While in a classic vehicle setup the vacuum required for the brake booster is generated by the air manifold while the engine is running, an increasing number of today's vehicle powertrains being direct injection, diesel, hybrid electric or full electric, there is typically much lower levels of vacuum created. This requires the brake system to supply on/off command signals to an electric vacuum pump to maintain vacuum amplification or provide extra levels of power to stop the vehicle if vacuum is depleted. It is critical that the amount of engine vacuum available is known and that this data is transferred to the brake controller in order for sufficient amounts of brake boost to be delivered.
"TRW's vacuum sensor has been developed using the knowledge we gained in creating satellite pressure sensors for crash sensing applications," said Marc Bolitho, director, global sensors engineering, for TRW Automotive. "While vacuum sensors for brake applications are not new, TRW has constructed what we believe to be a highly reliable and flexible configuration with solid performance, packaging and price competitiveness, and this allows us to offer our customers a combined actuation and sensor offering."
The new TRW vacuum sensor contains a sensing element and a signal conditioning ASIC on one silicon die. The unit is manufactured in a sealing housing with venting membrane. Output voltage is provided either analog 0 to 5V or via a digital SAE J2716 SENT interface. The unit operates in the temperature range between -40°C and +125°C.
The first application of TRW's vacuum sensor is expected to launch in 2013.