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[Automotive] Optimization of Oil Lubrication Path of HEV Transmission Systems

ㆍProduct: HEV and EV Transmission System

ㆍAnalysis Goal: Optimization of lubrication pathway to improve HEV and EV lubrication and cooling

PDF File Download 'HEV Transmission Lubricant Simulation' (Click)

Optimization of Lubricant Oil Path of HEV Transmissions

Transmission oil plays two roles: lubricating the parts that are rotating at high speed in order to minimize wear, and responding to the heating phenomenon of each part as an appropriate coolant. But if the amount of lubricant oil is excessive, it becomes a resistance factor against each rotating part, which may have a negative effect on fuel efficiency.

Therefore, oil path inside a HEV transmission has been optimized using simulation, and the optimal amount of oil has been determined through visualization and quantification process of the model in order to get the best lubricating and cooling efficiency.

Process for HEV Transmission Simulation

① Configuration of dynamic model that includes rotation and other motions using the entire transmission model

② Co-simulation of the transmission lubricant oil model and the dynamic model

③ Benchmark test using an actual transmission (check for the quantitative behavior of lubricant oil)

④ Comparison between the actual test and simulation results, as well as detailed parameter tuning

⑤ Visual/numerical comparison and analysis of oil behavior effects according to the change of design parameters using the basic virtual model for which detailed parameter tuning has been completed

⑥ Analysis of the simulation results according to various changes in driving conditions (acceleration, deceleration, and steering of a vehicle)

Key Technologies for Analysis

Dynamic modeling of the internal parts of an HEV transmission (RecurDyn Professional)

Highly precise fluid modeling according to the characteristics of lubricant oil (Particleworks)

Bi-directional exchange of essential physical quantity between high speed rotating parts and oil (Co-simulation)

ㆍHigh speed particle simulation technology through GPGPU (Particleworks GPU Solver)

Calculation of pressure and speed between lubricant oil and the related parts with high accuracy

Comparison between the actual model and analysis regarding oil supply amount

Images: Courtesy of Hyundai Motors
(From the presentation of “Churning oil path optimization process development” by Chulmin Ahn at VDI Dritev 2018)

Toolkits for HEV Transmission / Lubricant Oil Optimization




ㆍParticleworks Interface

Customer Challenges

• Performance degradation of JEV transmission caused by inefficient oil lubrication

• Demand for improved lubrication performance compared to the existing products

• Difficulty to evaluate the lubrication performance because of the invisibility of transmission inside

• Excessive time and cost to review various designs and operating conditions through prototypes

Solutions for Lubricant Oil Path Optimization

Time and cost reduction through quantitative performance evaluation of various designs and operating conditions (load torque and oil level) by visualizing lubricant oil behavior inside the transmission using both RecurDyn and Particleworks simulation.

Change of lubricant oil behavior according to the guide configuration

Lubricant Oil Behavior Inside the HEV transmission


ㆍOptimization of the oil path configuration that is required in the initial stage of HEV transmission design through highly precise visualization and quantification of the oil flow inside the transmission through simulation

•The resistance (Drag) created by oil on each rotating part, which is consistent with the test result, can be estimated in advance. The optimal amount of transmission lubricant oil can be proposed based on such estimation.

Other Applications of lubricant oil simulation

Analysis of changes in load torque according to the difference in temperature of lubricating oil

ㆍRelationship between viscosity and load torque according to the temperature of lubricant oil after turning off the engine input torque

ㆍAnalysis of difference in reduction of speed according to lubrication status between the states that have different temperatures (viscosity)

Analysis of the reduction gear train which takes into consideration the viscosity of lubricating oil

ㆍVisualization of the lubricant oil spray which was not possible until now

ㆍThe effect of the gear output according to the load of oil viscosity can be designed to be closer to reality

Behavior analysis of lubricating oil spray inside the differential gearbox

ㆍAnalysis of load torque when viscous fluid (lubricant oil) has been added to the differential gear train robot

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