Comparison of fuel injection systems and a new combustion method for a direct injection two-stroke-cycle automobile engine

A study of a direct fuel injection 2-stroke engine as a new generation power unit was performed and concluded as follows.

• 1.(1) A comparison of fuel injection system candidates was made and the one-fluid high-pressure type was chosen.
• 2.(2) Adopting the high-pressure fuel system to a single-cylinder engine, stratified charge combustion was realized using the late injection.
• 3.(3) It was found that homogeneous charge combustion using the early injection would enable high power output.
• 4.(4) The “2-zone combustion” was also achieved by injecting the fuel twice within one cycle.

     

Studies on the measuring method of the total friction loss of internal combustion engines

In the present study a new test method is investigated to measure the total friction loss of engines over the whole range of speed and load. It is based on the idea that the friction loss close to the true one of fired and braked engines can be measured by the run-out method because the temperature mainly influencing the friction loss is almost stable for the short run-out test duration. From the test results and the comparison with those measured by other conventional test methods, the following becomes evident:

• 1.(1) The total friction mean effective pressure slightly increases as the revolution speed becomes high, but it decreases as either the load or the cooling water temperature becomes high.
• 2.(2) The total friction mean effective pressure measured by the present method is smaller than that measured by the run-out method, the motoring method or Willans-line method, but it is larger than that measured by the indicated pressure diagram method.

     

A study of recycling technology for paint-coated plastic automotive bumper

Our objective was to eliminate the harmful effect of paint films in recycled material. Our study focused on the molecular bonding in paint resin, and reached the following conclusions:

• 1.(1) The use of a modifier allows the ether linkage in the paint film to be cleaved and its molecular structure changed. This resulted in improved compatibility between the paint and the material, rendering the paint film chips harmless.
• 2.(2) Bumpers molded using modified recycled material meet requirements for mechanical properties, moldability, paintability and surface quality.
• 3.(3) A continuous process where modification and pelletization are done simulataneously in a twin-screw extruder was achieved. This reduces the number of process steps and processing time, while providing improved productivity and economies.

     

Development of new decompression brake for heavy duty diesel engine

We have developed a new decompression brake, which incorporates an original operation mechanism, in answer to user demands for more powerful brake performance. This decompression brake improves braking power by more than 50% compared with a conventional exhaust brake, when operated in tandem with an exhaust brake. The decompression brake contributes to safe driving, to alleviate driver fatigue, and to prolong brake lining life.This paper reports on the following subjects:

• 1.(1)The principle and development of the original operation system.
• 2.(2) Test results of performance and load analysis.

     

Numerical Simulation and Experimental Verification of the German Roller Rig for Rail Vehicles*

SUMMARY

A numerical simulation model of the roller test stand located at Munich and loaded by a bogie is discussed including its technical structure, the governing physical equations of motion and the structure of the simulation program.

Both, the set up of the mathematical and numerical models time and the computation time of simulation runs have been considerably reduced (by a factor of 20) using formula manipulation programs.

Simulation results concerning the

• starting behaviour of a bogie,

• stationary limit cycle behaviour of bogies with ideal and wear profile and

• influence of gauge changes and spring/damper modifications on limit cycle behaviour of a bogie are presented, some of which are compared with experimental results gained from test facility measurements. The simulation results are in good agreement with the experimental results and provide an experimental verification of the roller rig simulation model presented.

     

Assessment of a semi-Hertzian method for determination of wheel–rail contact patch

Wheel–rail contact calculations are essential for simulating railway vehicle dynamic behavior. Currently, these simulations usually use the Hertz contact theory to calculate normal forces and Kalker's ‘FASTSIM’ program to evaluate tangential stresses. Since 1996, new methods called semi-Hertzian have appeared: 5 Kik, W. and Piotrowski, J. A fast approximate method to calculate normal load at contact between wheel and rail and creep forces during rolling. Paper presented at the 2nd Mini-conference on Contact Mechanics and Wear of Rail/Wheel Systems. July29–31, Budapest.  [Google Scholar] 7 Ayasse, J. B., Chollet, H. and Maupu, J. L. 2000. Paramètres caractéristiques du contact roue-rail. Rapport de Recherche INRETS n225, ISSN 0768–9756 (in French) [Google Scholar] (STRIPES). These methods attempt to estimate the non-elliptical contact patches with a discrete extension of the Hertz theory. As a continuation of 2 Ayasse, J. B and Chollet, H. 2005. Determination of the wheel–rail contact patch in semi-Hertzian conditions. Vehicle System Dynamics, 43(3) [Google Scholar], a validation of the STRIPES method for normal problem computing on three test cases is proposed in this article. The test cases do not fulfill the hypothesis required for the Hertz theory. Then, the Kalker's FASTSIM algorithm is adapted to STRIPES patch calculus to perform tangential forces computation. This adaptation is assessed using Kalker's CONTACT algorithm.     

Development of active front wheel steering control system keeping stable region in driving phase diagram

This paper presents a new active steering control system based on driving phase diagram (β _fr ?δ _f diagram). In order to make state variables to follow those of nominal vehicle model that was developed under no consideration of disturbance, Quadratic Programming Problem (QPP) is formulated, where time varying objective function minimizes the differences between nominal and actual parameters. The steering characteristic in active steering control system changes when the vehicle faces disturbance such as crosswind and flat tire, and driver tries to counteract it after recognizing the change. The proposed method defines a stability region on β _fr ?δ _f diagram. In order to make β _fr and δ _f remain in the stability region, a new model predictive controller is proposed. While conventional controllers are restrictive to satisfy the β _fr ?δ _f diagram based stability condition, the proposed controller ensures solution space and also plays a direct role to minimize the evaluation function in the constrained optimal control problem.     

System power loss optimization of electric vehicle driven by front and rear induction motors

Power loss optimization aiming at the high-efficiency drive of front-and-rear-induction-motor-drive electric vehicle (FRIMDEV) as an effective way to improve energy efficiency and extend driving range is of high importance. Different from the traditional look-up table method of motor efficiency, power loss optimization of the dual- motor system based on the loss mechanism of induction motor (IM) is proposed. First of all, based on the power loss characteristic of FRIMDEV from battery to wheels, the torque distribution optimization model aiming at the minimum system power loss is put forward. Secondly, referring to d-q axis equivalent model of IM, the power loss functions of the dual-IM system are modeled. Then, the optimal torque distribution coefficient (β _o) between the two IMs is derived, and the theoretical switching condition (T _sw) between the single- and dual-motor-drive mode (SMDM and DMDM) is confirmed. Finally, a dual-motor test platform is developed. The derived torque distribution strategy is verified. The influence of motor temperature on β _o and T _sw are tested, and the correction models based on temperature difference are proposed. Based on the system power loss analysis, it can be confirmed that, under low load conditions, the SMDM takes priority over the DMDM, and the controller of the idling motor should be shut down to avoid the additional excitation loss. While under middle to high load conditions, even torque distribution (β _o = 0.5) is preferred if the temperature difference between the two IMs is small; otherwise, β _o should be corrected based on dual-motor temperatures. The theoretical T _sw derived without dealing with temperature difference is a function only of motor speed, while temperature difference correction of it should be conducted in actual operations based on motor resistance changing with temperature.     

Investigation of Occupant Lower Extremity Injures under Various Overlap Frontal Crashes

Objective

With widely usage of restraint system, fatal injuries to occupants have been largely limited while non-fatal lower extremity injuries have not been effectively improved. The present study aims to investigate occupant lower extremity injuries under realistic impact environments.

Methods

A biofidelic lower extremity model, a dummy model and a car cab model were combined to set up a realistic impact environment. Three typical frontal impact groups were simulated. Occupant global lower kinematics, long bone axial force and bending moment were presented to in-depth investigate lower extremity injury mechanism and tolerance.

Results

Various overlap frontal impacts cause totally different lower extremity kinematics in the combination of structural invasion and restraint system effects. The femur fracture occurred at a small axial force of 7.57 kN combing a substantial bending moment peak of 172 Nm. Ankle joint injuries were found in 100 % and 25 % overlap impacts that present large tibial axial force and joint rotation angle.

Conclusions

Overall results indicate that a coupling threshold of femur axial force and bending moment is of rationality to predict global femur fracture. The ankle joint injury occurrence is significantly related to the coupling effects of tibia axial force and excessive self-kinematics.

     

PantoCat statement of method

The pantograph–catenary dynamic interaction analysis program (PantoCat) addresses the need for a dynamic analysis code able to analyse models of the complete overhead energy collecting systems that include all mechanical details of the pantographs and the complete topology and structural details of the catenary. PantoCat is a code based on the finite element method, for the catenary, and multibody dynamics methods, for the pantograph, integrated via a co-simulation procedure. A contact model based on a penalty formulation is selected to represent the pantograph–catenary interaction. PantoCat enables models of catenaries with multiple sections, including their overlap, the operation of multiple pantographs and the use of any complex loading of the catenary or pantograph mechanical elements including aerodynamic effects. The models of the pantograph and catenary are fully spatial being simulated in tangential or curved tracks, with or without irregularities and perturbations. User-friendly interfaces facilitate the construction of the models while the post-processing facilities provide all quantities of interest of the system response according to the norms and industrial requirements.     

Load Transfer Analysis of a Bus Bay Section Under Standard Rollover Test Using <Emphasis Type="Italic">U</Emphasis>*<Subscript>M</Subscript> Index

Bus rollover accidents are receiving increasing attention due to the associated high fatality rate. In order to improve the bus structural performance during the rollover collision, it is necessary to investigate how the impact force is transferred within the bus superstructure. This paper introduced a method for studying the load transfer behavior of the bus superstructure during the standard rollover test by using the U * _M index. A bus bay section was used as the sample structure to demonstrate the proposed method. The result of the paper reveals that the load transfer analysis based on the U * _M index can provide engineers with the insight of the structural issues and the direction to improve the structural performance, which cannot be accomplished through the conventional finite element analysis.     

Analysis of a special purpose vehicle’s behaviour after an edge drop-off onto a soft shoulder

The article concerns the dynamics of a four-axle 20 ton special purpose vehicle in the driver’s panicky defensive manoeuvre resulting from edge drop-off of wheels onto a soft shoulder. A calculation model in the PC-Crash software environment has been developed to include the complex mechanism of the soft soil response to the wheel movement. The analysis of the results indicates the danger manifested by strong wheels vibrations, instantaneous change of vehicle steerability characteristics and a high rate of increase of the yaw angle and vehicle pitch during braking with steered wheels turned. The calculations indicate an extremely adverse effect of the phase of vehicle oversteer which in the analysed motion of the vehicle lasts over 1.5 s. The calculations prove that in such a short time the driver has very little chance of any practical response to the non-typical behaviour of the vehicle which otherwise is, in general, understeered.     

Gain scheduled linear quadratic tracking system tuned optimally by covariance matrix adaption evolutionary strategy for automotive engine coldstart control

In this paper, a gain scheduled linear quadratic tracking system (LQTS) tuned optimally by an evolutionary strategy (ES) is devised to reduce the total tailpipe hydrocarbon (HC) emissions of an automotive engine over the coldstart period. As the engine’s behavior during coldstart operations is nonlinear, the system dynamics is clearly analyzed and represented by a number of separate linear models generated based on a coldstart model verified by experimental data. An independent LQTS is then implemented for each of these linear models. In this way, several control laws are created, and the corresponding gains are calculated for each of the independent control laws. ES is then used to tune the adjustable parameters of LQTSs to calculate the control inputs, namely air/fuel ratio (AFR) and spark timing (Δ), such that the resulting exhaust gas temperature (T _exh) and engine-out HC emissions (HC _raw) be close to a set of optimum profiles. This enables the controller reduce the cumulative tailpipe hydrocarbon emissions (HC _cum) to the highest possible extent. To demonstrate the acceptable performance of the proposed controller, an optimal controller derived from the Pontryagin’s minimum principle (PMP) is also taken into account. Based on the results of the conducted comparative study, it is shown that the proposed control technique has a very good performance, and also, can be easily used for real-time applications, as it consumes a remarkably trivial computational time for calculating the controlling commands.