• Journal of Drive and Control
• /
• v.17 no.3
• /
• pp.47-56
• /
• 2020

As a shift control of automatic transmission was managed with the electronic control unit (ECU), shift quality which is a measure of shift shock during gear change has markedly improved. However, the initial clutch pressure control of the clutch filling phase should continue to rely on the predetermined control input since the input and output speeds are unchanged until the shifting process attains the inertia phase. It is critical to minimize the clutch response time and control the clutch pressure accurately at the end of clutch fill to achieve quick shift response and smoothness. Advanced transmission companies have adopted an auto calibration method which establishes the databases for the clutch piston fill-up attributes and the frictional characteristics of the disks. In this study, a distinctive auto calibration algorithm for forklift transmission under development is proposed and verified with the real-vehicle test. The experimental calibration results showed consistent turbine dynamics at the initial stage of shifts with the properly calibrated clutch-fill control parameters. By using this technique, it is necessary to finalize the shift control for the various operation conditions.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.9
• /
• pp.947-954
• /
• 2011

Drive-train friction loss in a vehicle may account for 4% of its total fuel consumption loss. An ATF W/C (auto-transmission fluid warmer/cooler) plate-fin heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between the auto-transmission fluid and coolant. The use of an ATF W/C heat exchanger can result in a fuel economy improvement of about 1% in vehicles. An experimental setup for testing the thermal performance of an ATF W/C plate-fin heat exchanger is developed. In this study, the influence of the ATF and coolant, flow rates, and temperature on the efficiency of an ATF W/C heat exchanger are investigated experimentally. From the experimental data, a simple correlation for predicting the efficiency of an ATF W/C heat exchanger is proposed. On the basis of this correlation, the fuel economy of a vehicle with and without an ATF W/C heat exchanger is compared by using Simulink. Finally, it is shown that the fuel economy is improved by 0.992% when an ATF W/C heat exchanger is installed in the vehicle.

• The KSFM Journal of Fluid Machinery
• /
• v.13 no.6
• /
• pp.71-76
• /
• 2010

This study has investigated numerically and experimentally the flow characteristic of air-cooling fan for transmission oil cooler in the large-size diesel engine. Impellers of cooler were composed of eight normal-scale and eight small-scale blades in the zig-zag pattern. In order to increase the discharge pressure of cooling fan, turbo type of fan blade is proposed in the impeller for transmission oil cooler. The fluidic performance of cooling fan has been estimated numerically by using the commercial code and experimentally carried out with reference on AMCA Standard 210-99. As a result, it is confirmed that the numerical result for performance curve is in good agreement with experimental data.

• Journal of Drive and Control
• /
• v.18 no.2
• /
• pp.46-55
• /
• 2021

A forklift is a powered industrial vehicle used to lift and move materials over short distances. Nowadays, almost all forklifts are equipped with an automatic transmission due to its improved operator comfort and increased productivity. Thanks to marked improvement of transmission control unit equipped with highly-advanced microcontrollers, recently developed automatic transmission for forklift have various auxiliary functions such as creep, auto retardation, and automatic shift with excellent shift quality. This paper deals with the creep function which enables one to maneuver a forklift at the designated low speed by slip control of clutches. The design of creep function was based on four modes of creep operation depending on the status of the operator's shift lever and accelerator pedal. Control algorithms and control parameters for each mode were designed to achieve the desired static and dynamic performance. Vehicle test for the designed creep function was carried out with an independently developed embedded controller. Test results confirmed good creep speed control without speed error at a steady state with a mild shift shock during mode changes by stepping or releasing the accelerator.

• Journal of Drive and Control
• /
• v.15 no.4
• /
• pp.30-38
• /
• 2018

Electronic control units (ECUs) are currently popular, and have evolved further towards the high-end application of autonomous vehicles in the automotive industry. Such digital technologies have also become widespread, in agriculture and construction equipment. Likewise, transmission control of high-speed tracked vehicles is based on the transmission control unit (TCU), performing complex gear change control functions, and diagnostic algorithms (a TCU's self-diagnostic and reporting capability of malfunction data through CAN communication). Since all functions of TCU are implemented by embedded-software, it is hardly possible to analyze specifications by reverse engineering. In this paper a real-time transmission simulator adaptable to TCU is presented, for analysis of diagnosis algorithm and standards. Signal simulation circuits are deliberately designed considering electrical characteristics of TCU inputs and various analysis tools, such as analog input auto scan function, and global output enable switch, are implemented in software. Test results from hardware-in-the-loop simulator verify tolerance time for each error, as well as cause of fault, error reset conditions.

• Journal of the Korean Society of Safety
• /
• v.29 no.3
• /
• pp.114-120
• /
• 2014

The purpose of this study is to conduct the study of the combustion and thermal characteristics through transportation oil for the analysis of fire hazard. Transportation oil breaks down into fuels such as diesel for civilian demands, gasoline, DF1(diesel for military), high sulfur diesel(for marine), kerosene and JP1(for aviation), and lubricants like brake fluid, power steering oil, engine oil, and automatic and manual transmission oil. The experiments of flash point, ignition point, flame duration time, heat release rate were carried out using TAG closed cup flash point tester(AFP761), Cleveland open cup auto flash point analyzer(AFP762), KRS-RG-9000 and Dual cone calorimeter. As a result, the fuel's ignition points were lower than lubricants, especially that of gasoline was not conducted as it has below zero one. Gasoline has the highest ignition point of about $600^{\circ}C$, while the other fuels showed $400{\sim}465^{\circ}C$. For flame duration time, lubricants had over 300 seconds, but fuels had less than 300 seconds except high sulfur diesel(350 seconds). Total heat release rate ranged $287{\sim}462kW/m^2$ for lubricants and gasoline showed the highest total heat release rate, $652kW/m^2$.