The hot wire type air flow meter is an important tool in measuring the quality of air flow. It is widely used in Santana engine, and in this article, the application in exhaust analyzer is introduced. The basis theory, the basic principle and the application of the hot wire type air flow meter are presented. The main purpose of this article is using the least square method to fit the standard data, calibrating accurately the flow meter by making the curve fit, then using standard tests and comparing the results with the standard current flux at last. The results indicate that the hot wire type air flow meter is accurate in surveying the flux of the exhaust gas.

In the detection of the oil viscosity, rotatory viscometer continues using viscosity-torque transduce principle. Its most trouble of detection structure is the system accuracy problem caused by the elastic element output torque. Development of high precision torque sensor is one of the key technologies to improve the accuracy of torque measurement. This paper, in detail, introduces the detection principle of rotatory viscometer, the working principle of the hairspring, and the specific design of hairspring, which includes the materials, diameter, length, coils of hairspring.

Analyzing the strain expression referring to Castigliano’s Theorem after analysis of the tripod type universal coupling under drawing force comes to the simplified mode of tripod type universal coupling. And with the help of simplified mode, it concludes that the minimum strain occurs when the radius of cross-section of the circlip equals to the depth of groove. After setting material attributes, boundary conditions, contacts of the tripod type universal coupling, and static simulation with the finite element method in SolidWorks, the strain of the universal couplings is carried out. Theoretical analysis and simulation results show that when the radius of cross-section of the coupling equals to the depth of groove, the strain is minimum.