نشریه تحقیقات موتور
پیاپی 75 (تابستان 1403)

Each driving cycle designed to monitor fuel consumption, vehicle emissions, and the specific driving patterns of a region is created to facilitate better planning and enhancement of local standards. In this study, the Real Driving Emissions (RDE) method, regarded as one of the most precise techniques for determining driving cycles, was employed. To gather the necessary data, GPS from mobile phones was utilized while traveling on city buses through the streets of Kermanshah. This data collection included recording speed, acceleration, duration of constant speed, deceleration, altitude, number of braking events, and the duration of stops along the route from origin to destination. The research employed the clustering of real city data and the K-means method to derive the driving cycle for Kermanshah’s city buses. Analyzing the collected data reveals that bus drivers in Kermanshah tend to avoid rapid acceleration and high constant speeds, leading to reduced fuel consumption in the city bus cycle, indicating that this behavior is intentional and aimed at this goal.

In this study, the ECU program of the OM 457 diesel engine manufactured by IDEM Co. has been recalibrated and SCR after-treatment has been installed in the exhaust gas path of the engine, which finally, by maintaining the engine performance, its emission standard has been upgraded to Euro 5EEV and the fuel consumption of the engine has also been reduced. With this upgrade, the engine's CO2 emissions have also been reduced, which is effective in reducing greenhouse gases that cause global warming. Also, this upgrade was done without changing the engine design and only by recalibrating the ECU program, which also reduced the cost of the project. The basic OM 457 engine has the Euro 3 emission standard, which is installed on vehicles with DPF after-treatment, which DPF has a high price, and also DPF is very sensitive to the sulfur in fuel, and the gasoil used in the country has high sulfur, causing early DPF failure. Now, with this upgrade of the engine emission standard to Euro 5 EEV without using DPF, the problem of price and sensitivity of DPF to sulfur has also been solved, and SCR after-treatment is not sensitive to fuel sulfur.

Oil coking and turbine seal ring melting are among the main failure modes of engine turbochargers. During the turbocharged internal combustion engine development process, the cooling and lubrication system must be checked for appropriateness of the desired condition for turbocharger journal bearing and seal rings which the turbocharger manufacturer defines. In this study turbine and compressor journal bearings and turbine seal ring temperature were measured at different engine speeds and loads as well as coolant flow at engine hot shutdown conditions. Also, the effect of inlet coolant temperature and exhaust gas entering the turbine housing on bearing housing temperature was investigated. The experimental test shows that maximum heat transfer from the turbocharger to the coolant is at the engine's maximum power point. Among measured points, turbine sealing always has the highest, and Compressor journal bearing has the lowest temperature. Coolant and oil temperature are the main controllers of temperatures but exhaust gas temperature has a lower effect on temperature at the investigated point.

The cylinder-piston reciprocating mechanism has been one of the most dominant designs since the invention of internal combustion engines. By reducing friction between the cylinder and piston of the engine, the reciprocating movement of the piston can be made possible, easily. The pressure inside the cylinder during the compression and expansion strokes is much higher than in the crankcase. Due to the movement of the piston inside the cylinder and its temperature change during the engine operation, a clearance needs to be between them. The clearance creates some crevices between the cylinder chamber and the crankcase. By placing the open-mouthed elastic rings in their special grooves on the piston, some serious flowing obstacles are created. However, in addition to the loss of work, the friction between the rings and cylinder can cause the relative motion of the rings in their grooves during the reciprocating movement of the piston and change the blowby geometry, so the ring friction forces are important. In the present work, an accurate experimental method is proposed and used to measure the friction of a ring with a cylinder applying a mass-pulley-string set, equipped with a displacement measurement sensor. After the experimental-analytical estimation of pulley-resistant torques, to extract the friction force of the ring, the friction force was measured and calculated in two states piston without ring and piston with ring. The results showed that the friction force of a compression ring was 2.87 N and although the piston under vertical movement had no noticeable lateral load, it was observed that its friction force was about 77% of the compression ring friction.

Electrochemical deburring is one of the methods commonly used to remove machining inclusions on small and micron scales. High accuracy, speed, and possibility of deburring at the same time are the advantages of this electrochemical deburring method. In this article, the effect of applying ultrasonic waves on the electrochemical deburring process for combustion engine oil spring rings has been investigated. The effect of the input parameters ultrasonic power, electric current intensity, and electrolyte temperature on the output parameter of material removal rate in electrochemical deburring was investigated. The experiments were designed by the Response Surface method and based on the Box-Behnken design so that each of the three mentioned input parameters is changed in three levels and the other input parameters are kept constant. Two types of electrolytes used in these experiments are NaCl and NaNO3. The maximum applied ultrasonic power is one hundred watts. The results of the experiments showed that the effect of ultrasonic on the material removal rate under the same conditions of the maximum electrolyte temperature and the maximum electric current intensity for the oil spring ring in the case of using NaCl electrolyte is 83.87% and in the case of using NaNO3 electrolyte is 89.74%. Also, for the oil spring ring, the average increase in material removal rate for NaNO3 electrolyte compared to NaCl electrolyte is 19.6%. After the ultrasonic power, electric current intensity and electrolyte temperature, respectively, had a positive effect on increasing the rate.

Nowadays, due to environmental concerns and the hope of limiting the phenomenon of pollution in mega-cities, the development of electric vehicles is one of the priorities of the modern industrial world. Lithium batteries are the main type of batteries used in electric cars. Temperature is one of the most effective parameters on the performance of these batteries because it can change their chemical behavior. Due to the necessity of battery operation in a suitable temperature range and with uniform temperature distribution, it is necessary to adopt a suitable and optimal cooling method with efficiency and reliability at all three levels of cell, module, and battery pack. One of the passive methods for thermal management in batteries is the use of a heat pipe. The purpose of this research is to use a new arrangement for the heat pipe in a battery module and study its temperature effects with the help of 3D thermal model simulation and an electrochemical model (NTGK) to simulate this system. The results of this study indicate that this new arrangement can improve the temperature uniformity distribution of the battery module by 4.1%.