At this year's electronica in Munich, Germany, Bosch launches the SMP14x, a pressure sensor for hydraulic pressure measurement in automatic transmissions. With a response time of less than 1 millisecond, the sensor measures pressure to operate the clutch with high precision.
The pressure sensor now enables smooth, fast gear shifting without judders, which translates into a higher degree of driving comfort for the driver and passengers.
The SMP14x features a hermetically-sealed, 100% leak-tight metal package, with high media resistance. This ensures that the electronics do not come into contact with the hydraulic fluid and guarantees a long lifetime for the sensor. Measurement is performed by four piezo resistors located on a membrane, with the resistors connected to a wheatstone bridge. When pressure is applied, the membrane flexes, which changes the resistance value, and thereby the electrical bridge signal. This resulting signal is processed and calibrated by an ASIC.
For greater design flexibility, the SMP14x provides both analogue and digital interfaces, with the digital interface enabling more precise pressure sensing and the possibility of submitting diagnostic information. Sensors with ten to ninety bar maximum pressure are possible, with a total of over thirty sensor variants to meet diverse customer requirements. The sensor is one of the smallest available for this application, helping make integration as easy as possible. It is provided in a 3-pin disc-shaped metal housing with a diameter of less than 17.5mm and height of less than 11.0mm.