The HTT-01 is the first pressure sensor to combine the robustness, long life and accuracy required for continuous pressure measurement on diesel and petrol engines. With its thin-film strain gauge measuring element, the novel device provides continuous pressure data to enable increased efficiency of internal combustion engines, thereby enabling improvements to fuel economy and performance while reducing wear to improve reliability and cut maintenance requirements.
Although monitoring the pressure in each cylinder of an internal combustion engine is not a new concept, the quartz sensors that have been traditionally used are both expensive and unsuitable for long-term use. As a result, the procedure has been limited to engine development studies and calibration rigs. Conversely, low-cost devices such as spark-plug washers and boss-type sensors are not sufficiently accurate to enable the fine degree of control required to optimise engine performance.
The HTT-01 is a joint development between Sensor-Technik and Imes, and uses a patented high-temperature thin-film strain gauge on a stainless-steel diaphragm. The design features integral temperature compensation, enabling the HTT-01 sensor to operate at temperatures up to 300C, comfortably accommodating the temperatures encountered in the engine compartments of all types of vehicles, as well as in generators and marine applications.
The standard pressure measuring range is 0-300bar, although versions with other ranges are available. A wide safety margin is provided, with an overload pressure rating as high as 800bar. Under typical combustion conditions, the HTT-01 sensor will provide a pressure reading accuracy of between +/-1 and +/-2% of full-scale output, accounting for hysteresis, nonlinearity and thermal shock effects. This is combined with a guaranteed lifetime of 500 million pressure cycles.
The sensor runs from a single supply between 18 and 30V DC, and produces 4-20mA outputs of both pressure and temperature, providing a simple interface solution via its M12 plug connector.
Physically, the HTT-01 sensor is similar in size to a standard automotive spark plug, 65mm long with a diameter of 18mm. It is separated from its electronics by a 2m-long cable.
