• Journal of Auto-vehicle Safety Association
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• v.14 no.2
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• pp.7-13
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• 2022

This paper presents a yaw moment control based on estimated mass for manual-shift commercial vehicles. In yaw moment controller, parameter uncertantiy of vehicle mass is important because the desired yaw moment depends on vehicle parameter. However, in the case of commercial vehicle, the weight of the loaded vehicle is more than twice as much as compared to the unloaded vehicle. The proposed algorithm estimates the vehicle mass by using the longitudinal dynamic and gear shifting characteristics. The estimated mass is used to adaptively modify the vehicle parameters. In addition, this paper estimates the chamber pressure of a pneumatic brake and generates the target yaw moment through on/off valve control. MATLAB/Simulink and Trucksim were performed under sine with dwell test. The results demonstrate that the proposed algorithm improves the lateral and rollover stability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.32-38
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• 2020

Cargo train braking uses the pressure changes in the air braking pipe to operate the braking tightening and releasing service repeatedly. Air-braking release failure means partial braking caused by a failure of the variable load valve after the driver handling the brake release. This phenomenon causes wheel flaws while driving a wagon, resulting in wheel breakage or train derailment. This study developed the air-braking release failure proof valve considering the technical requirements of the railway operation corporations. In addition, a durability test of the valve was carried out using a braking performance simulator, and its operating performance was evaluated from the pneumatic history under cyclic braking conditions. The warranty life of this valve was assessed by performing 160,000 cycles of testing of 12 prototypes in accordance with the zero-failure test method, considering the number of braking cycles while driving the wagon. During the durability test, the pneumatic input time, output time, and release velocity were almost constant. The warranty life of this valve was 59,860 times the 95% confidence level, which means that it can be operated without trouble for four years when the valve is installed in the bogie of the wagon.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1009-1015
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• 2011

In this study, in the high expansion cycle was conduced by variable valve timing system composition to close intake valve late, and in the intake air reduction on the low compression was solved by supercharging pressure. In this wise, by constituting Diesel-Atkinson cycle, this study looked into a possibility of thermal efficiency improvement. As a result, there was improvement in thermal efficiency and output in a whole range of closing timing from ABDC $40^{\circ}$ to ABDC $80^{\circ}$. However, after ABDC $70^{\circ}$ of closing timing, the thermal efficiency increase was getting smaller. As the result of the study, the optimum intake valve closing timing was about ABDC $70^{\circ}$, high loading territory of engine was more effective than low loading territory, and engine operation in middle loading territory was stable. At this time, brake thermal efficiency was 12.5% higher than ordinary engine on average.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.470-476
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• 2019

The braking force for a train is generally provided by compressed air. The pressure valve system that is used to apply appropriate braking forces to trains has a complex flow circuit. It is possible to make a channel shape that can increase the flow efficiency by 3D printing. There are restrictions on the flow shape design when using general machining. Therefore, in this study, the compressed air flow was analyzed in a pressure valve system by comparing flow paths made with conventional manufacturing methods and 3D printing. An analysis was done to examine the curvature magnitude of the flow path, the diameter of the flow path, the magnitude of the inlet and reservoir pressure, and the initial temperature of the compressed air when the flow direction changes. The minimization of pressure loss and the uniformity of the flow characteristics influenced the braking efficiency. The curvilinear flow path made through 3D printing was advantageous for improving the braking efficiency compared to the rectangular shape manufactured by general machining.

• Tribology and Lubricants
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• v.21 no.5
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• pp.227-235
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• 2005

This paper presents a tribological study on the failure cases of automatic transmission components in a passenger car. The automatic transmission system is composed of torque converter, clutch, brake, planetary gear, and valve body controlling oil pressure of an automatic transmission fluid. The most largest influence components in an automatic transmission are a torque converter and clutch plate in which are influenced by a wear and torque converting energy loss. The failure case study of an automatic transmission indicates that the tribological design and maintenance technologies should be considered as a key design concept. This means that the failure and power energy loss come from the friction, wear and a oil leakage of an automatic transmission, which is related to the oil seal and O-ring seal failures.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.45-53
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• 1998

Traction control systems(TCS) improve vehicle acceleration performance and stability, particularly on slippery roads through engine torque and/or brake torque control. This research mainly deals with the engine control algorithm based on adjustment of the engine throttle valve opening. Hardware-in-the-loop simulation(HWILS) is carried out where the actual hardware is used for the engine/automatic transmission and TCS controller, while various vehicle dynamics are simulated on real-time basis. Also, use of the dynamometer is made in order to implement the tractive force that a road applies to the tire. Although some restrictions are imposed mainly due to the capability of the synamometer, simplified HWILS results show that the slip control algorithm can improve the vehicle acceleration performance for low-friction roads.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.3
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• pp.90-96
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• 1995

In general, natural gas engine converted from gasoline engine has disadvantage of power decrease. In order to increase power output in natural gas engine, the improvement of in-cylinder flow motion has been believed as the most effective method. In this study, the geometry of combustion chamber in 4 valve DOHC natural gas engine is modified, and in-cylinder flow patterns is analyized. Also engine performance is evaluated according to the modification of in-cylinder flow motion.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.184-191
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• 2003

HILS(Hardware-ln-the-Loop Simulation) is a scheme that incorporates hardware components of primary concern in the numerical simulation environment. Due to its advantages over actual vehicle test and pure simulation, HILS is being widely accepted in automotive industries as test benches for vehicle control units. Developed in this study is a HILS system for VDC(Vehicle Dynamics Control) with a valve control system that modulates the brake pressures at low wheels. Two VDC control logics were developed and tested in the HILS system. Test results under various driving conditions are presented in this paper.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.2
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• pp.44-52
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• 1993

In this study, the characteristics of decreasing exhaust gas of diesel engine was examined in dual fuel method by using commertial LPG for automotive. LPG was supplied to engine intake port by fumigation method and flow rate was controlled by using the needle valve. LPG supply ratios were 0, 20, 30% of total fuel amount to be supplied to engine by mass base. We investigated the effect of LPG supply ratio on exhaust gas concentrations related to excess air ratio and engine load at 1600, 1800, 2000 rpm. Soot concentration decreased about 30% in proportion to the increase of the LPG supply ratio. NOx concentration decreased in proportion to the increase of the LPG than diesel only and the increase rate was higher at low engine load. BSFC(Brake specific fuel consumption) was lower in proportion to the increase of the LPG supply ratio at high engine load and to the decrease of LPG supply ratio at low engine load.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.110-110
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• 2000

In this paper, an antilock brake system (ABS) for commercial vehicles is studied by considering the design of a fuzzy Logic controller with pulse width modulation (PWM). PWM method is used for generating solenoid valve inputs in order to cope with the chattering problem caused by the conventional on/off control The sliding mode observer is designed to estimate the vehicle longitudinal velocity and it is used to calculate the wheel slip ratio. The effectiveness of the proposed control algorithm was validated by simulations performed with a nonlinear 14-DOF vehicle model including the dynamics of the brakes.