scholarly journals Study of Injection Method for Maximizing Oil-Cooling Performance of Electric Vehicle Motor with Hairpin Winding

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 747
Author(s):  
Taewook Ha ◽  
Dong Kyu Kim
Keyword(s):  
Electric Vehicle ◽  
Flow Rate ◽  
Film Formation ◽  
Formation Rate ◽  
Cooling Performance ◽  
Oil Film ◽  
Injection Method ◽  
Cooling Method ◽  
Oil Flow ◽  
Oil Injection

The oil injection method was studied to maximize the cooling performance of an electric vehicle motor with a hairpin winding. The cooling performance of the motor using the oil cooling method is proportional to the contact area of the oil and the coil. A numerical analysis was conducted to examine the effect of the spray nozzle type on the oil flow. The dripping nozzle forms the thickest oil film on the coil, making it the most effective for cooling of hairpin-type motors. Subsequently, an experimental study was conducted to optimize the nozzle diameter and number of nozzles. When the inlet diameter and number was 6.35 mm and 6, the oil film formation rate was 53%, yielding the most uniform oil film. Next, an experiment was performed to investigate the effects of the oil temperature and flow rate on the oil flow. The oil film formation rate was the highest (83%) when the oil temperature was 40 °C and the flow rate was 6 LPM.

scholarly journals Experimental Study on Behavior of Coolants, Particularly the Oil-Cooling Method, in Electric Vehicle Motors Using Hairpin Winding

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 956
Author(s):  
Taewook Ha ◽  
Nyeon Gu Han ◽  
Min Soo Kim ◽  
Kyu Heon Rho ◽  
Dong Kyu Kim
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Management ◽  
Flow Rate ◽  
High Performance ◽  
Cooling Performance ◽  
Oil Film ◽  
Cooling Method ◽  
Motor Cooling ◽  
The Heat Transfer Coefficient

This paper analyzes the characteristics of oil behavior in the oil-cooling of motors with hairpin winding to understand how to maximize cooling performance. The oil cooling is performed by directly spraying oil onto the motor components. The results show that as the temperature of the oil increases, the viscosity decreases, and the oil film is formed more evenly; however, oil splashing also increases. Similarly, as the flow rate increases, oil splashing also increases, but the amount of oil forming the oil film increases. However, the oil film is not affected by the rotor’s rotation. In contrast, the immersed oil is found to be closely related to the rotor’s rotation. As the rotational speed increases, the immersion oil is mixed with the air, and oil churning occurs. The mixing phenomenon increases as the temperature and flow rate of the oil increases. The higher the oil level, the greater the oil churning. As the oil is mixed with air, the heat transfer coefficient decreases, which adversely affects the thermal management of the motor. As a result, when considering the oil film and the immersion oil, the optimal oil temperature, flow rate, and oil level are at 60 °C, 0.140 kg/s, and 85 mm, respectively. The results of this paper give important information about EV motor cooling and can contribute to the development of high-performance motors.

Oil Flow in a Full Journal Bearing

1961 ◽  
Vol 83 (2) ◽  
pp. 312-314
Author(s):  
Donald F. Hays
Keyword(s):  
Flow Rate ◽  
Journal Bearing ◽  
Hydrodynamic Pressure ◽  
Leakage Rate ◽  
Positive Pressure ◽  
Pressure Gradients ◽  
Oil Film ◽  
Oil Flow ◽  
Pressure Area ◽  
Side Flow

An analysis was made of the oil flows occurring in a full journal bearing with a continuous oil film. The flow rate into the bearing was determined at the section of greatest clearance and the rate of outflow was determined at the section of least clearance. The rate of side flow or leakage rate was determined by considering the flow across the boundary of the positive pressure area only and is the flow resulting from the hydrodynamic pressure gradients. It does not include the effects of any specific oil feed mechanism.

Study on Subsynchronous Vibration With Tilting Pad Journal Bearing Under Starved Lubrication

2018 ◽  
Author(s):  
Rimpei Kawashita ◽  
Tadasuke Nishioka ◽  
Shimpei Yokoyama ◽  
Makoto Iwasaki ◽  
Shuichi Isayama ◽  
...  
Keyword(s):  
Flow Rate ◽  
Journal Bearing ◽  
Damping Ratio ◽  
Leading Edge ◽  
Rotor System ◽  
Experimental Results ◽  
Oil Film ◽  
Tilting Pad ◽  
Oil Flow ◽  
Starved Lubrication

Industrial machines such as gas and steam turbines require high efficiency and reliability. Direct lubricated bearings have been developed and installed to reduce mechanical losses. In recent years, it has been reported in the literature that subsynchronous vibration can occur to rotor shafts with direct lubricated tilting pad journal bearings under reduced oil flow rate conditions. In this study, a test rig with a 200 mm diameter and 3.5 meter long rotor supported by a direct lubricated tilting two pad journal bearing was constructed. The primary critical speed is 2100rpm and rotational speed is 3600rpm. The oil-starved area, the non-oil film layer region at the leading edge of the bearing pads, was measured by observing oil film pressure in the bearing clearance with pressure transducers on the rotor surface. A sine sweep excitation test was carried out by using an inertial shaker installed on the bearing housing and the damping ratio of the rotor system was measured. Measured data showed that a larger starved area at the leading edge of the bearing pads due to reduced oil feeding results in a smaller damping ratio, and an increase in the natural frequency of the rotor. Experimental results of two types of oil feeding nozzles were compared with respect to the correlation between starved area and damping ratio of the rotor system, and a relationship between oil flow rate and starved area was discussed. A method for modeling bearing coefficients under starved lubrication has been proposed based on thermo-hydrodynamic lubrication (THL) analysis. A numerical analysis of a finite element-transfer matrix model of the test rotor with the bearing coefficients calculated by the proposed method is carried out, and it is found that the analytical results are in broad agreement with the experimental results.

Pad attitude adjusting moment in large multi-pocket pivoted pad used in static oil journal bearing

2017 ◽  
Vol 69 (4) ◽  
pp. 605-611
Author(s):  
Xizhi Ma ◽  
Miaomiao Li
Keyword(s):  
Flow Rate ◽  
Ball Mill ◽  
Large Scale ◽  
Journal Bearing ◽  
Operating Conditions ◽  
Content Type ◽  
Oil Film ◽  
Hydrostatic Bearing ◽  
Attitude Adjustment ◽  
Oil Flow

Purpose Large scale is a trend of the ball mill, so the loads on their bearings become very large, bearing operating conditions turn into more severe. The moment of inertia to their pivot of the pad increase significantly, so it leads to the difficult of the pad attitude adjustment and makes the pad tilting angles time response slow, the key factor to effects attitude adjustment is the oil film moment to the pad pivot at unbalance position. the oil film moment and its effect factors must be studied in the design of the bearing used in ball mill. Design/methodology/approach Models about the lubrication of multi-pocket pivoted pad hydrostatic bearing is established, the complicated relationship of the oil flow rate between the oil pockets are taken into account. Finite differential method is used to solv the model, and theroy of finite element method is use to calculate the oil flow rate out of the pocket edges. Newton’s methods are used to determine the pressure of pockets.The pad tilting moment to its pivot is numerically analyzed. Findings The tilting moment to its pivot is set as an indicator of the ability for a pad to adjust its attitude. The effects of the diameter of throttling capillary and the pocket area on the attitude adjusting capacity is studied. Relations between the attitude adjustment capacity for a pad and there effects factors are presented. Practical implications The methods and results have the special reference to the design and operation of multiple pockets tilted pad hydrostatic journal bearing. Originality/value Methods to studied the pad attitude adjustment are given in the article for the multi-pocket pivot pad hydrostatic beairng.The influence factors on pad attitude adjusting capacity are discussed for a this specail kind hydrostatic bearing, the how the factors influence the pad tilting angle adjustment are presented.

The Role of Emulsification and Interfacial Tension Ift For the Enhanced Oil Recovery Eor in Surfactant Flooding

2021 ◽  
Author(s):  
Xiaoxiao Li ◽  
Xiang'an Yue ◽  
Jirui Zou ◽  
Lijuan Zhang ◽  
Kang Tang
Keyword(s):  
Interfacial Tension ◽  
Crude Oil ◽  
Flow Rate ◽  
Oil Recovery ◽  
Surfactant Flooding ◽  
Displacement Efficiency ◽  
Oil Viscosity ◽  
Oil Film ◽  
Oil Flow ◽  
Emulsifying Capacity

Abstract In this study, a visualized physical model of artificial oil film was firstly designed to investigate the oil film displacement mechanisms. Numerous comparative experiments were conducted to explore the detachment mechanisms of oil film and oil recovery performances in different fluid mediums with flow rate. In addition, the of influencing factors of oil film were comprehensively evaluated, which mainly includes: flow rate, surfactant behaviors, and crude oil viscosity. The results show that, (1) regardless of the viscosity of crude oil, flow rate presents a limited contribution to the detachment of oil film and the maximum of ultimate oil film displacement efficiency is only approximately 10%; (2) surfactant flooding has a synergistic effect on the oil film displacement on two aspects of interfacial tension (ITF) reduction and emulsifying capacity. Giving the most outstanding performance for two oil samples in all runs, IFT reduction of ultra-low value is not the only decisive factor affecting oil film displacement efficiency, but the emulsifying capability plays the key role to the detachment of oil film due to effect of emulsifying and dispersing on oil film; (3) the increasing flow rate of surfactant flooding is able to enhance the detachment of oil film but has an objective effect on the final oil film displacement efficiency; (4) flow rate have the much influence on the detachment of oil film, but the most easily controlled factor is the surfactant property. The finding provides basis for oil film detachment and surfactant selection EOR application.

scholarly journals Newly Developed Motor Cooling Method Using Refrigerant

2019 ◽  
Vol 10 (2) ◽  
pp. 38
Author(s):  
Hidemasa Fujita ◽  
Atsushi Itoh ◽  
Tohru Urano
Keyword(s):  
Fuel Cell ◽  
Electric Vehicle ◽  
Electric Vehicles ◽  
Hybrid Electric Vehicle ◽  
Fuel Cell Vehicle ◽  
Water Cooling ◽  
Test Results ◽  
Cooling Performance ◽  
Cooling Method ◽  
Motor Cooling

One of the greatest issues for electric vehicles such as an electric vehicle (EV), a hybrid vehicle (HV), a plug-in hybrid electric vehicle (PHEV) and a fuel cell vehicle (FCV) is further improvement of effective motor cooling, since higher rated torque is achieved with higher cooling performance. In this paper, we introduce and propose a newly developed motor cooling method we tested using refrigerant, comparing with conventional water cooling. Test results show higher cooling performance of refrigerant cooling, which achieved the rated torque 60% higher than that of water cooling.

Numerical and Experimental Study for Unsteady Oil Film Thickness of the Rotating Cylinder Chamber Wall

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Zhao Jingyu ◽  
Liu Zhenxia
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Film Thickness ◽  
Rotation Speed ◽  
Film Formation ◽  
Rotating Cylinder ◽  
Chamber Wall ◽  
Wall Heat Transfer ◽  
Oil Film ◽  
Oil Flow

The oil film thickness on the bearing chamber wall directly affects the wall heat transfer efficiency, so a fundamental study on the motion of oil film on the rotating cylinder has been conducted to this end. On the one hand, the rotating cylinder test rig was designed, and an ultrasonic measurement system was established to measure the dynamic oil film thickness. On the other hand, the unsteady oil film heat and mass transfer movement model was also established, and the numerical simulation to solve oil film motion by using computational fluid dynamic (CFD) commercial software was carried out. Meanwhile, on the basis of study on the oil film formation process and film thickness verification, the oil film distributions on the chamber wall with rotation speed and oil flow rate were analyzed and studied. Results show that the oil film on the rotating chamber wall experiences a development process from the oil film formation to basic stability, about 1.0 s in this paper. And comparison between the numerical and experimental data shows that the maximum error between experimental data and numerical simulation is 7.76%. Moreover, for the oil film distributions in the stable state, oil film thickness shows a trend of decreasing with the increasing of rotation speed, but increasing with the increasing of oil flow rate. The research here will provide the basis for subsequent study of the interaction between oil film motion and the wall heat transfer.

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