Meeting stringent exhaust emission requirements: Dual-mode differential pressure sensor

As people's environmental awareness grows, exhaust emission regulations become increasingly stringent, requiring us to take more measures to reduce harmful components in automobile exhaust, such as installing gasoline particulate filters (GPFs) in exhaust aftertreatment systems. The performance of exhaust aftertreatment systems depends largely on the sensors that are used. The differential pressure sensor is used to measure the differential pressure between the inlet and outlet of the GPF, so that the OBD can diagnose the blockage and removal of the particulate filter, and is also used for closed-loop control of the "regeneration" process. To this end, Sensata Technologies has developed a dual-mode differential pressure sensor for the GPF system based on microelectromechanical (MEMS) technology to meet the requirements of the harsh exhaust working environment. Compared with the differential pressure sensor, the dual-mode differential pressure sensor adds a signal of the downstream relative pressure, which can meet the requirements of some OEMs for improving the diagnosis of GPF removal and rear-end pipeline shedding. Sensata Technologies' dual-mode differential pressure sensor is based on rich technical experience and professional products, and plays an important role in this field.

The working principle of the dual-mode differential pressure sensor is as follows: the upstream and downstream pressure ports of the GPF are connected to the P1 and P2 pressure ports of the dual-membrane differential pressure sensor respectively. The two pressure sensitive elements inside the sensor are connected to the upstream and downstream air pressures respectively. The tiny deformation caused by the pressure on the sensitive elements is input into the ASIC through the Wheatstone bridge. The ASIC amplifies and processes the tiny signal and outputs the SENT digital signal for use by the on-board computer (ECU).

The dual-mode differential pressure sensor has the following advantages and characteristics: First, the sensor uses two sensitive elements and one chip to complete the processing of two signals to obtain the GPF differential pressure and downstream relative pressure signals; second, it uses the SENT signal to realize three PIN outputs of differential pressure and relative pressure signals; third, the sensing element is protected by a special gel, using a ceramic substrate and corrosion-resistant wires to withstand the exhaust gas environment; fourth, it has excellent drainage performance and anti-icing design; fifth, the modulation circuit has real-time temperature compensation to ensure high-precision output in different temperature ranges.

The dual-mode differential pressure sensor uses Sensata's reliable and mature sensitive components and control modules. Currently, this product has been mass-produced by mainstream OEMs in Europe and China. Compared with its peers, the dual-mode differential pressure sensor designed by Sensata has higher accuracy, better durability, higher quality, and rich practical application experience. Currently, the global market share of this product is close to 50%, and the domestic market share is 60%.

Sensata Technologies' dual-membrane differential pressure sensor integrates two pressure sensing elements to achieve differential pressure measurement and relative pressure measurement, providing the ECU with differential pressure signals at the front and rear ends of the GPF and relative pressure signals at the rear end of the GPF. This product design can meet the stringent exhaust gas environment requirements of the GPF, providing accurate signal output and reliable product life. Currently, this product has been mass-produced in Sensata Technologies' manufacturing plants in Malaysia and Changzhou, China, and can quickly respond to the application needs of global customers.