Accurate and fast positioning of large aircraft component is of great importance for Automated Alignment System. The Ball joint is a widely-used mechanical device connecting the aircraft component and Automated Alignment System. However, there are some shortcomings for the device in man-machine engineering, such as the entry state of the ball-head still needs to be confirmed by the workers and then switched to the locking state manually. To solve above problems, a new positioning mechanism is present in this paper, which consists of a ball-head and a ball-socket. The new device is equipped with a monocular vision system, in which a calibrated industrial camera is used to collect the images of the ball-head. And then, the 3-D coordinate of the ball-head center is calculated by a designed algorithm, which combines the symmetry of the sphere and the principle of projection transformation, guiding the positioner to capture the ball-head. Once the ball-head gets into the ball-socket, the pneumatic system inside the ball-socket will drive the piston to move to the specified location. Meanwhile, the amount of…

The magneto-rheological (MR) damper featuring piston bypass holes is an MR damper with improved mechanical properties relative to conventional MR dampers. It brings much better ride comfort for occupants by minimizing the harshness component from disturbing the smooth ride of vehicles. However, few studies on this MR damper featuring piston bypass holes are found. This work is aimed to study the principle that this MR damper works on by experiment, modelling and simulation. The MR damper featuring piston bypass holes is tested on MTS system. A mathematical model for the MR damper is established. Head loss and local head loss caused by the viscosity of the MR fluid are both adopted in the mathematical model. The Eyring model is adopted to describe the mechanical behavior of MR fluid. The result of simulation is in good agreement with experimental data. When the local head loss is eliminated from the mathematical model, simulation accuracy decreases. These results indicate that the local head loss due to sudden contraction and sudden expansion at entrance and exit of piston bypass…

Late-cycle soot oxidation in heavy-duty (HD) diesel engine low-swirl combustion was investigated using single-cylinder engine and spray chamber experiments together with engine combustion simulations. The in-cylinder flow during interactions between adjacent flames (flame-flame events) was shown to have a large impact on late-cycle combustion. To modify the flame-flame, a new piston bowl shape with a protrusion (wave) was designed to guide the near-wall flow. This design significantly reduced soot emissions and increased engine thermodynamic efficiency. The wave’s main effect was to enhance late-cycle mixing, as demonstrated by apparent rate of heat release after the termination of fuel injection. Combustion simulations showed that the increased mixing is driven by enhanced flow re-circulation, which produces a radial mixing zone (RMZ). The leading edge of the RMZ extends toward the center of the piston bowl, where unused ambient gas is available, promoting oxidation. The wave also enhances mixing in the trailing edge of the RMZ when it detaches from the wall, accelerating the burn-out of the RMZ. This flame interaction effect was isolated and studied further using a…

Designing automobile brake systems is generally complex and time consuming. Indeed, the brake system integrates several components and has to satisfy numerous conflicting government regulations. Due to these constraints, designing an optimal configuration is not easy. This paper consequently proposes a simple, intuitive and automated methodology that enables rapid optimal design of light vehicle hydraulic brake systems. Firstly, the system is modeled through cascaded analytical equations for each component. A large design space is then generated by varying the operational parameters of each component in its specific reasonable range. The system components under consideration include the brake pedal, the master cylinder, the vacuum-assisted booster, the brake line and the brake pistons. Successful system configurations are identified by implementing the requirements of the two most relevant safety homologation standards for light vehicle brake systems (US and EU legislations). Ergonomics constraints and the compensation for the fluid losses are then retained as further design requirements. Finally, the optimal design identification is carried out based on overall system braking performance and the cost. Particularly, optimal braking performance is…

The automotive market’s need for ever cleaner and more efficient powertrains, delivered to market in the shortest possible time, has prompted a revolution in digital engineering. Virtual hardware screening and engine calibration, before hardware is available is a highly time and cost-effective way of reducing development and validation testing and shortening the time to bring product to market. Model-based development workflows, to be predictive, need to offer realistic combustion rate responses to different engine characteristics such as port and fuel injector geometry. The current approach relies on a combination of empirical, phenomenological and experienced derived tools with poor accuracy outside the range of experimental data used to validate the tool chain, therefore making the exploration of unconventional solutions challenging. An alternative method that is less data and user experience dependent, is therefore needed to enable radical improvements in performance to be delivered without compromising the time to market.In this work, a pragmatic engine development process using a combination of a 0-D combustion Stochastic Reactor Model (SRM) provided by LOGESoft and non-combusting ‘cold’ CFD is used.…

Variable compression ratio (VCR) technology has long been recognized as a method for improving the automobile engine performance, efficiency, fuel economy with reduced emission. This paper presents a design of hydraulically actuated piston based on the VCR piston proposed by the British Internal Combustion Engine Research Institute (BICERI). In this design, the compression height of the piston automatically changes in response to engine cylinder pressure by controlling the lubrication oil flow via valves in the piston. In addition, numerical models including piston kinetic model, oil hydraulic model, compression ratio model and etc., have been established to evaluate the piston properties. The oil flow characteristics between two chambers in VCR piston have been investigated and the response behaviors of VCR engine and normal engine, such as compression pressure and peak cylinder pressure, are compared at different engine loads. Moreover, the energy losses because of VCR piston vibration at high engine loads in firing cycles have been calculated. According to the analysis results, both of energy loss and related percentage in piston work output rise with engine…

The majority of engine out particulate emissions are released in the first several minutes of cold start operation, in large part due to cold piston surface temperatures which fall well below the boiling point of the injected fuel. Use of topology optimization methods to increase piston surface temperatures is a promising approach to solve this challenge, but existing applications have focused largely on basic small-scale canonical scenarios in the steady-state. In this work an algorithm was developed and demonstrated which is aimed at optimizing the internal structure of an engine piston to increase piston surface temperatures during the early phases of engine cold start, while subjected to a peak temperature limit during hot steady-state conditions. Finite difference heat transfer models of a light duty aluminum engine piston were created and an evolutionary optimization algorithm in conjunction with the Lagrange Multiplier Method were used to develop optimal piston topologies. Overall the methods developed represent a unique successful application of topology optimization techniques to an unsteady thermal system at a practical scale. Various optimal designs were generated…

The distribution of lubricating oil plays a critical role in determining the friction between piston skirt and cylinder liner, which is one of the major contributors to the total friction loss in internal combustion engines. In this work, based upon the experimental observation an existing model for the piston secondary motion and skirt lubrication was improved with a physics-based model describing the oil film separation from full film to partial film. Then the model was applied to a modern turbo-charged SI engine. The piston-skirt FMEP predicted by the model decreased with larger installation clearance, which was also observed from the measurements using IMEP method at the rated. It was found that the main period of the cycle exhibiting friction reduction is in the expansion stroke when the skirt only contacts the thrust side for all tested installation clearances. The main reason for lower skirt friction with larger clearance is greater amount of oil available during the expansion stroke.

The crankshaft translates the reciprocatory motion of the piston into rotary motion. A flywheel is generally connected to the crankshaft to reduce the vibrating characteristic of four stroke cycle. Counterweights are added for each reciprocating piston to provide engine balance while operating. Gasoline engines have curtailed compression ratio therefore shorter stoke length as a deduction have higher RPM in comparison to diesel counterpart. A crankshaft is subjected to enormous stresses, potentially equivalent of several tones of force. Failure of the crankshaft is predominantly due to violent vibrations, insufficient lubrication, excessively pressurized cylinder. This research aims to examine the stress subjected to acute points on a crankshaft. Three dimension model of 4 stroke single cylinder engine crankshaft is modeled using SolidWorks v18. End conditions were applied taking into consideration the engine mountings of the crankshaft. Stresses were applied to crankpin to replicate the forces of a running engine. Twisting moment causes Shear stresses; bending moment are determinant of the tensile and compressive stresses. This research was conducted for two different materials Stainless steel and Epoxy carbon…