Coupling problem between the dynamical and tribological behaviors in the piston-liner systems of multi-cylinder IC engines

This paper deals with the coupling problem between the dynamic behaviors and the tribological behaviors of the piston-liner systems in multi-cylinder internal combustion engines. Firstly, based on the correction of some errors in the equation of piston secondary motion, which have been employed by many authors for several years, a detailed mathematical model for the coupling problem between the dynamical and tribological behaviors in the piston-liner systems of multi-cylinder internal combustion engines is presented. Secondly, the lubrication and friction between the liner and piston in each cylinder is included applying the average flow model of the Reynolds equation. Thirdly, the vibration of each liner is computed through the finite element model of a four-cylinder engine block, by which not only the liner motions caused by the block vibration but also the local vibration and the local static deformation of each liner can be figured out and taken into account. Through theoretical analysis and computation, some conclusions can be drawn as: 1) Both the liner vibration and piston motion are different for different cylinder in a multi-cylinder internal combustion engine, and hence different piston-liner systems will have different tribological behaviors. 2) Different liners have coincident dynamic response on the whole, especially for the lower frequency components. However, differences still exist among the vibrations of different liners, and these differences are mainly owing to the higher frequency components. 3) The impacts of liner vibrations on the tribological behaviors in piston-liner systems are primarily ascribed to its higher frequency components.

Research and Application of an Electro-hydraulic Synchronous Control System for Bridge Lifting

With the increase of bridge reconstruction schemes, synchronous lifting of a bridge is more and more widely used. In order to solve the problems associated with the synchronoas lifting of a bridge, a multi-cylinder synchronous lifting power and monitoring system has been developed. This is a distributed control system, which is com- posed of an industrial computer workstation, a programmable logical controller and a hydraulic control system. The system can achieve distributed control and centralized operation of actuators, and centralized management of infor- mation. It not only can implement multi-cylinder synchronous lifting with an unbalanced load, but also can moni- tor the pressure, displacement and stress at each lifting point. The performance of the multi-cylinder synchronous system is verified through its application to several bridge lifting engineering projects. The details of such a project are given.