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The reduction of greenhouse gas is becoming increasingly important for humankind, and vehicles with low CO₂ emissions have a part to play in any reduction initiatives. Diesel engines emit 30% less CO₂ than gasoline engines, so diesel engines will make an important contribution to the overall decrease. Unfortunately diesel exhaust gas contains particulate matter (PM) which may cause health problems, and such PM emissions are regulated by law. In order to reduce PM, especially soot, diesel particulate filters (DPFs) are widely fitted to diesel vehicles. A DPF can remove more than 99% by weight of soot from exhaust gas under normal operating conditions, and they are one of the most important methods to achieve any regulation targets. But if the system malfunctions, the PM emissions may exceed the regulation limit. To detect such PM leakage, on-board diagnostics (OBD) are required.

This paper report on a newly designed, flat, angular- rate sensor consisting of a Hammer Headed, Double-T Structure, vibrating element made from a single quartz crystal. Our optimized sensor's performance is highly reliable because the resonator uses the vibrations in only one plane of a monolithic quartz crystal that is highly stable under operating conditions, especially temperature changes. This sensor fulfills the stringent demands required for automobile electronic control systems. The performance of the newly developed quartz, angular-rate sensor is highly reproducible by using one of the most stable materials known, the single quartz crystal. This is in contrast to polycrystalline materials such as ceramics or deposited polysilicon. The proposed structure can be manufactured in high volume and at low cost, which are requirements for automotive applications.

A compact, angular-rate sensor module has been developed using a flatly supported, quartz sensing element of double T-shaped resonators. The sensing element has both drive and pickup resonators in the same plane of a Z-cut quartz wafer to detect angular-rate motion perpendicular to the plane so that the sensor module can fit in space 5.6mm high along with its sensing axis. Thanks to good stability of the quartz, and symmetric structure of the double T-shaped resonators, the sensor module also can achieve small offset drift, high S/N (Signal to Noise ratio), and excellent immunity to vibration noise. In this paper, the principle of the sensing element is briefly explained followed by detailed discussions on the angular-rate sensor module's: 1) Structure 2) Performance and 3) Field Testing.

A newly designed, flat, angular-rate sensor consisting of T-shaped vibrating resonators using a single quartz crystal has been developed for automotive, chassis-control systems and vehicle navigation systems. For these systems, the sensor is required to be highly stable under operating conditions. Our newly developed sensor's performance is highly reliable because the resonator is made of quartz that is highly stable under operating conditions, especially temperature changes. The newly developed quartz angular sensor is easy to fabricate because it has a 2-dimensional structure. This structure facilitates the mass production of the sensor at low cost; a requirement for automotive industry use. The flat sensor (0.3mm thick) is fabricated from z-cut quartz and shows promising performance for automotive applications. The flat structure also has the advantage of being easily mounted in flat, narrow spaces.