JTEKT (France)

High-speed deep-groove ball bearings for the eAxle of electric vehicles must adapt to higher rotational speed conditions, because eAxle motor speed increases to downsize the unit. Therefore, it is necessary to clarify the lubrication process of ball bearings at the high rotational speeds to prevent seizure and wear. The oil-film thickness between outer-ring and ball, and the oil distribution around balls in 6008 deep-groove ball bearings incorporating experimental quartz outer rings were measured under high-speed conditions, with speeds exceeding 20,000 min−1. These measurements were carried out by employing the three-wavelength flash-light optical interferometry method and the UV-LED light-induced fluorescence method. It was found that the oil-film thickness did not increase even when the rolling speeds increased, which is in contrast to the EHL theory under sufficient lubrication condition. Contrary to the EHL theory, these phenomena can be attributed to the oil starvation and lowering effective viscosity of oil containing bubbles resulting from aeration under high-speed conditions.

Surface hardening treatment is used to have strength to mechanical parts, and carburizing and quenching are the most widely used. There are reports on various carburizing efforts to deal with recent environmental issues. The authors have proposed an ultra rapid carburizing above the eutectic temperature, due to realize in-line carburizing. Since this is an unprecedented carburizing treatment method, setting the carburizing conditions that are suitable for efficiency has been the future challenge.

CVT chains are widely used in vehicles because the slip between parts is small, which enables efficient power transmission. However, the intermittent motion of CVT chain pins entering and leaving the pulleys causes undesirable vibration in the whole chain, and affects the basic performance of the CVT. Therefore, it is important to investigate the influence of the geometrical specifications of the chain on this vibratory motion. This study focused on the pin-pulley slip length when the pins enter and leave the pulleys, and a mathematical model for the power loss of a CVT chain was developed. The validity of this model was verified and confirmed experimentally. In addition, the influence of the shape of chain components on power loss was also investigated. In particular, the influence of the position of the contact point between the pins and pulleys on power loss was investigated both theoretically and experimentally, and geometric parameters were optimized. As a result, the model formulated in this paper can be used to investigate measures for reducing CVT power loss.

Osmanl Devleti'nden koparacaklar topraklar zerinde kendilerine ait bir devlet kurmak isteyen Ermeniler iin Birinci Dnya Sava'nn km olmas byk bir frsat olarak nitelendirildi. Gemiten itibaren tilaf Devletleri ile bu hususta birlikte hareket eden Ermeniler, Osmanl Devleti iindeki ayrlk faaliyetlerini Birinci Dnya Sava'nn yaklamasyla birlikte zellikle Rusya gdmnde devam ettirdiler

<div class="section abstract"><div class="htmlview paragraph">Lane Centering Control System (LCCS) is a lateral Advanced Driving Assistance System (ADAS) with low acceptance. One of the main reasons is that the centering trajectory can’t satisfy different drivers, which is more obvious in the curve condition. So LCCS adaptive to different drivers needs to be designed. The trajectory planning module is an important part for LCCS. It generates trajectory according to the road information for the vehicle control module to track. This paper uses road information obtained from the scenario established in Prescan, and the trajectory planning method proposed can generate trajectories for different drivers in the curve condition. To achieve the goal, this paper proposes a trajectory planning method which contains lateral path planning and longitudinal speed planning. Firstly, the overall strategy of “road equidistant segments division” is used to describe the road information. Secondly, the path planning method establishes objective functions for four typical driving modes respectively, including shortest length, minimum curvature, centering driving, and minimum heading angle deviation, which solved by quadratic programming. Then the mixed mode path is obtained by weighting four different paths. Thirdly, a speed planning method is proposed. The speed profile is described by the natural cubic spline and it’s based on the generated path which considers different constraints of longitudinal and lateral acceleration of different drivers and the trajectory is generated by coupling speed profile with the path. Finally, the co-simulation of Matlab/Simulink and Prescan is carried out in different scenarios, and the simulation result is analyzed. The simulation result shows that the trajectory planning method proposed in this paper can generate trajectories for different drivers under the constraints of the tire dynamics, and the feasibility of the algorithm is verified.</div></div>

Because of increasing number of motors which used for cars and spread of hybrid vehicles and electric vehicles, rack & pinion gear which used for automotive electric power steering is required to improve transmission efficiency. In former research, it was found that sliding velocity is related to transmission efficiency. In this research, new test rack & pinion gears which designed by focusing sliding velocity are designed and made. And their transmission efficiencies are measured. As a result, it found that the smaller sliding velocity is, the higher transmission efficiency is. And, the larger sliding velocity is, the lower transmission efficiency is. Result of this research suggested the method designing high efficiency rack & pinion by focusing gear dimensions related to sliding velocity and making module smaller, tooth depth smaller, number of teeth larger, and rack shift coefficient smaller in order to make sliding velocity smaller.

We have been developing an inverted pendulum type robotic wheelchair with the ability to climb stairs. This wheelchair has a seat slider and two rotary links between the front and rear wheels on each side. It is controled by a linear-quadratic regulator consisting of a center of gravity control mode and a rotary link control mode. In this paper, we focus on how to estimate the modeling errors in using this system and how to suppress the wheel motion, because modeling errors caused by payloads can cause the wheelchair to fall. We found that modeling errors cause wheel movement due to errors of the slider position and changes of the mass of the passenger. We proposed a method for estimating the slider position error and mass change, and confirmed that the method can be applied to correct the error.

Abstract Machine tools are required to realize high precision and high efficiency machining by various industry sectors. A machine tool has some driving systems to position cutting tools and workpieces, and hence driving units are required high speed and precision positioning. However, high speed feed motion causes thermal deformation due to generated heat at friction surfaces such as guideway, feed screw, and bearings, it deteriorates positioning accuracy of driving units. Thermal deformation of a ball screw is one of large error factors of lower positioning accuracy, and a cooling system for reducing thermal deformation is installed into machine tools. Since the cooling system needs additional cost and space in machining systems, a new method for minimizing thermal deformation is required. In this study, a new structure of ball screw is proposed in order to meet these requirements. A new ball screw which has a core pipe made of CFRP was developed. CFRP is one of composite materials which have light weight and low thermal expansion. This paper presents analysis results of a simplified FEM model of the ball screw and the basic experimental results of the developed ball screw. These results confirmed that the proposed ball screw was applied to high performance positioning system in machine tools.

<div class="section abstract"><div class="htmlview paragraph">Lane Keeping Assistance System (LKAS) is a typical lateral driver assistance system with low acceptance. One of the main reasons is that fixed parameters cannot satisfy individual differences. So LKAS adaptive to driver characteristics needs to be designed. Driver Steering Override (DSO) process is an important process of LKAS. It happens when contradiction between driver’s intention and system behavior occurs. As feeling of overriding will affect the overall experience of using LKAS, the design of DSO characteristics is worthy of attention. This research provided an adaptive design scheme aiming at DSO characteristics for LKAS by building Driver Preference Model (DPM) based on simulator test data from preliminary experiments. The DPM was to represent the relationship between driver characteristics indices and driver preferred system characteristics indices. So that new drivers’ preference can be predicted by DPM based on their own daily driving data with LKAS switched off. The inputs of DPMs are 27 lane changing driver characteristics indices which were extracted based on natural lane changing data. Principal Component Analysis (PCA) and correlation analysis were used during input-indices selection. The outputs of DPMs are 2 driver preferred system characteristics indices which can express driver’s preferred DSO characteristics. 6 participants took part in preliminary experiments for data collection and evaluation experiments. Their preferred system characteristic indices were calculated through the results of evaluation experiments. The building of DPMs was realized by Random Forest (RF) based on 6 participants’ lane changing driver characteristics indices and driver preferred system characteristics indices. The verification of DPMs’ effectiveness was realized by subjective evaluation. The result showed that DPMs can realize adaptive design of DSO characteristics for LKAS focusing on driver’s preference and improve driver’s acceptance.</div></div>

<div class="section abstract"><div class="htmlview paragraph">To reduce NOx and PM emissions in exhaust gas, after-treatment systems for low NOx emissions are being developed in combination with improvements of engine combustion. In recent years, the exhaust gas temperature has been dropping because of enhanced low-fuel consumption of the engine. Therefore, it is urgent to develop NOx reduction technologies that work at a low temperature under 200degC. Since NOx is reduced by reacting with ammonia supplied to the SCR catalyst, it is necessary to make the urea solution decompose into ammonia using the heat of the exhaust gas to supply sufficient ammonia to the SCR catalyst. However, both the decomposition reaction and hydrolysis reaction of the urea have insufficient exhaust heat, thus making it difficult for urea to decompose and hydrolyze to ammonia at a low temperature. To solve this problem, it focuses on forcibly decomposing the urea solution without depending on the exhaust gas temperature. We selected a urea reforming method in which the urea is directly heated using the glow plug as the heat source. In this study, we have considered further improvement of the NOx reduction performance at a low temperature with a view to improving the ammonia generation efficiency by urea reforming.</div></div>