Fit Clearance Research Articles

Design and Strength Analysis of Ultra-High Speed Permanent Magnet DC Rotor

The sintered neodymium-iron-boron (Nd-Fe-B) material is used in most of PM machines. The kind of PM materials has small tensile strength and cannot withstand large centrifugal force due to high rotational velocity. A nonmagnetic steel enclosure is needed to cover the PM material. The tensile stress of the PM can reduced by pre-pressure applied to the outer surface of the PM through shrink-fitting into the enclosure. Based on the elasticity theory and the elastic-plastic contact theory, in soft ANSYS it is feasibility to establish a finite element mechanical model of interference fit between the enclosure and motor rotor PM at high rotating speed. This paper simulates the effects of the temperature and rotating speed (centrifugal force) on the displacement and the contact pressure on the interference-fitting surfaces .By finite element non-linear contact model analysis, if setting up right fit clearance, this paper could ensure the security of the PM rotor under rotational velocity up to 300,000 r/min high and temperature up to 150°C.

The Determination of Using Limiting Clearance between Crank Pin and Bearing Bush in Volkswagen

Nowadays, the workers in automobile service enterprise use their experience to decide the using limiting clearance between crank pin and bearing bush. It is not enough to be scientific and accurate and it has caused waste on the manpower and financial resources. By using the theory of finite element and getting help from the large analysis software ANSYS, this paper calculated the limiting value of fit clearance between the crank pin and bearing bush scientifically which is in some engines belonged to the vehicle types of Volkswagen. Based on calculation, it has been found that the using limiting value of fit clearance between crank pin and bearing bush was generally small. The analysis and calculation in this paper has guiding significance to the development of automobile maintenance trade.

Design of Mechanical and Combustion System for Small Non-Road Diesel Engine to Meet the EPA IV Emission Regulations

Based on 1.9L small non-road diesel engine, mechanical and combustion system were redesigned and optimized to improve the emission performance. The engine block structure such as ribs, bolt hole depth and water jacket were optimized to improve the strength and stiffness and reduce the block’s distortion. The type of piston ring, piston skirt profile and their fit clearances were also optimized, and plat-honing cylinder liner was used to reduce the oil consumption. In combustion system, fuel injection pump, injection nozzle, fuel spray distribution and fuel supply advance angle were modified, combustion chamber was changed to small platform dumbbell-shaped chamber, and the closed-loop exhaust gas recirculation (EGR) system controlled by negative pressure was applied to trade-off the emissions of NOX and PM. The test results show that the emission performance of optimum diesel engine could meet EPA IV emission regulations.

CFD RESEARCH ON TEMPERATURE FIELD IN RADIAL CLEARANCE OF HYDRAULIC SPOOL VALVE

In medium and high-pressure system, temperature increases quickly because of throttling action. The fit clearance between spool and sleeve decreases because of the thermal expansion of the spool caused by temperature increment, so it is possible that spool is deadlocked in sleeve. Aim for deadlock of the sleeve and spool caused by throttling temperature increasing in hydraulic spool valves, a CFD(Computational fluid dynamics) model is made. Temperature field in radial clearance, when working pressure, radial clearance and opening varying, are analyzed. Then temperature field in radial clearance is obtained in various cases. The solution assayed, and the effects of working pressure, radial clearance and opening on temperate field in radial clearance are obtained. Theoretical reference is provided for designing spool valves.

焼結拡散接合法の開発

This report indicates the technical key-points of diffusion bonding method of ironbased green compacts during sintering comparing with the sinter-fit bonding method and some applications.The key-points are the material selections for assembled compacts which should be based on the difference of thermal expansion curves of both materials during sintering, the additive elements selections which should be based on the diffusion coefficient into iron, the fit clearance which should be maintained in the region of press fitting, the shape of iron powders and densities of green compacts.Most of applications of this technique are complex shaped parts of copy machines. And recently, the production of automotive engine parts is also started using this technique.

Application of fuzzy control to an inserting operation

Abstract Because of the difficulty of dynamic equations for the inserting operation and the advantage of fuzzy control for easy execution without knowledge of the mathematical models. We used the force feedback signal measured by a force sensor and a fuzzy controller to regulate the position of the peg. The control strategies include two control loops; in one a PID position controller move the peg vague position near to the hole, and in the other the fuzzy controller regulates the final position according to contact force. Between the two control loops we use an index to activate a switch. To verify the proposed control strategy, we performed experiments with a Cartesian manipulator system driven by AC servo-motors. The experimental results reveal that we can insert a peg into a hole with a fitting clearance less than 0.01 mm.