The SMP137’s primary area of application is in automatic transmissions. With a response time of less than a millisecond, it very precisely measures the pressure for activating a clutch. Pressure measuring in air-conditioning systems is a further area of application. The SMP137 has so far been available in sample item numbers – it will be available in large quantities from the fourth quarter of 2011. The SMP132 model for 22 bar maximum pressure will then follow in 2012.
New housing – pressure-resistant and easy to install
The disc-shaped housing of the SMP137 is approximately 19 millimeters in diameter, with an installation height of just under 10 millimeters. The new SMP13x series housing can withstand pressures of more than 100 bar. Another benefit: the electrical connections and the hydraulic connection are arranged on opposing housing surfaces – an important requirement for quick and easy installation.
Fed in at the sensor’s hydraulic connection, the hydraulic fluid presses against the monocrystalline measuring membrane. This membrane bends under pressure, while also sealing the sensor interior against the hydraulic fluid. Neither the sensor element attached to the rear of the membrane, nor the bond wires, nor the integrated electronics come into contact with the hydraulic fluid. The sensor therefore has a very high media resistance and a long service life.
The sensor element consists of a measuring bridge with piezoresistors, produced in MEMS technology. The level of the electric bridge signal changes proportionally to the bend of the membrane. This signal is processed by an analog ASIC integrated on same chip on which the membrane is located; it is then routed to the outside via the sensor’s electrical connections.
Bosch – globally leading manufacturer of MEMS sensors
Bosch has many years of experience in the development and production of hermetically packaged pressure sensors. More than 50 million of these sensors with TO-8 housings have been produced since production began in 1993. Bosch played a crucial role in the development of MEMS technology (microelectromechanical systems), which is used to produce tiny sensor elements. In total, the company has so far produced more than one billion sensors in MEMS technology – more than 220 million last year alone. This makes Bosch the world’s leading provider of MEMS sensors. The company’s portfolio includes pressure, acceleration, and yaw-rate sensors for numerous applications in the automotive industry and consumer electronics.
Contact:
Jochen Volm,
Phone: +49 7121 35-6651