Date:10th June 2012
Murata's MEMS sensors used in automatic
stop-start applications to save fuel
Murata is playing an important role in developing MEMS
products with cleaner technology that cuts fuel consumption.
The rising fuel prices and growing demand for cost reduction
and clean technology is a challenge for car manufacturers
to develop advanced solutions that meet these requirements.
The internal combustion engine stops while the vehicle
is at a standstill instead of idling the engine in automatic
stop-start systems that reduce fuel consumption. In addition
to detecting when the vehicle is stopped, inertial sensing
is used to hold the vehicle in place using the brakes while
the engine is restarted. The application requirements are
similar to electronic parking brakes, and in most cases
the measurement functionality is integrated with the ESC
system. Integrating inertial sensors with the ABS system
or using them as a standalone system is also feasible.
Although automatic stop-start systems are not new, until
recently the systems were used to stop the engine only when
the vehicle was at a standstill. In the latest developments,
the engine is stopped already when the vehicle's speed drops
below a certain limit. The objective is to maximize fuel
savings and minimize vehicle emissions.
Fuel is saved up to 10% in urban driving environments by
these automatic stop-start systems without requiring a substantial
redesign of the vehicle architecture compared to hybrid
technology, for example. Since these systems offer one of
most effective means of conserving fuel, both economically
and technically, the adoption rate among OEMs is picking
Murata's high accuracy MEMS inclinometers provide a means
of measuring vehicle inclination in a wide range of environmental
conditions. The internal mechanical gas damping of Murata's
MEMS sensors prevents them from picking up external signals
that can cause errors to the inclination measurement, and
the HW realization of the system is easier.
High accuracy versions of the SCA8X0 and SCA21X0 sensor
series are used in automatic stop-start applications, as
well as the gyro-combo sensor SCC1300 when integrated with
the ESC system.
For information on the MEMS sensors: http://www.muratamems.fi