Analysis of Counter-Rotating Roller Bearing in Different Mounting Configurations

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Wenjun Gao ◽  
Daniel Nelias ◽  
Zhenxia Liu
Keyword(s):  
Thermal Behavior ◽  
Load Distribution ◽  
Power Loss ◽  
High Speed ◽  
Roller Bearing ◽  
Total Power ◽  
Kinetic Behavior ◽  
Uniform Load ◽  
Roller Ring ◽  
Differential Speed

Advanced engine configuration studies have shown large advantages for an engine with counter-rotating spools with intershaft counter-rotating roller bearings. Mounted on two counter-rotating differential-speed hollow rotors, the bearing internal kinetic behavior, dynamic behavior, and then thermal behavior change greatly, causing a severe challenge to engine designers using traditional analysis methods. A special quasi-dynamic model for counter-rotating roller bearing is proposed, considering rings deformation and windage effects, to analyze the bearing mechanical and thermal behavior in different mounting configurations. Roller sliding and bearing heat generation are calculated and compared with experimental data to verify the model capabilities. It shows that the configuration that connects the inner ring to the high-speed rotor has life cycle advantage with more uniform load distribution, smaller roller/ring clearance, and lower cage speed. This leads to less drag loss due to the rotation of the rollers and cage assembly. The decrease of the total power loss is a key element to minimize the quantity of oil required to lubricate the roller bearing.

Reducing Gear Windage Losses From High Speed Gears

2000 ◽  
Author(s):  
Don D. Winfree
Keyword(s):  
Power Loss ◽  
High Speed ◽  
Total Power ◽  
Fort Worth ◽  
Trial And Error ◽  
Test Rig ◽  
Cost Overruns ◽  
Basic Set ◽  
Drive Trains ◽  
Reducing Gear

Abstract Windage losses in gearboxes account for a large portion of the total power loss in high-speed drive trains. Very little actual data has been collected specifically quantifying these losses. Traditional techniques to measure the effects of baffles in high speed gearing applications have been done by trial and error on very complex systems. This trial and error technique is used throughout the gearing industry to solve problems without isolating each individual gear windage effect. These solutions are usually sub-optimum. They cause time-consuming delays and cost overruns in many programs. This paper describes a gear baffle test rig that was built to quantify and minimize the gear windage losses in high-speed drive trains. These tests were conducted at the Lockheed Martin Aeronautics Company, Fort Worth Texas Facility. The intent of the gearbox baffle test rig was to isolate and measure the windage effects on a single high-speed bevel gear with various baffle configurations. Results of these tests were used to define a basic set of ground rules for designing baffles. Finally the set of ground rules was used to design an optimum baffle configuration.

Influence of angular misalignment on the tribological performance of high-speed micro ball bearings considering full multibody interactions

2020 ◽  
pp. 135065012094829
Author(s):  
Chengwei Wen ◽  
Xianghui Meng ◽  
Bugao Lyu ◽  
Jiaming Gu ◽  
Lin Xiao
Keyword(s):  
Fatigue Life ◽  
Axial Load ◽  
Power Loss ◽  
High Speed ◽  
Influencing Factor ◽  
Total Power ◽  
Angular Misalignment ◽  
Absolute Value ◽  
Life Model ◽  
Comprehensive Comparison

To study the angular misalignment effects on the high-speed micro ball bearing which is applied to the dental handpiece, an improved five-degree-of-freedom quasi-dynamic model considering full multibody interactions is established in this paper. Then the modified fatigue life model presented by Jones is adopted to further evaluate the influence of angular misalignment on the reliability of the bearing. The results show that the angular misalignment significantly influences the contact load and contact angle distributions as well as the skidding behavior under both pure axial load and combined axial and radial loads. After comprehensive comparison, it is found that the impacts of angular misalignment on total power loss and bearing fatigue life are different under the two types of loads. Under pure axial load, the total power loss increases consistently and the bearing fatigue life decreases significantly when the absolute value of angular misalignment becomes larger. However, under combined axial and radial loads, the effects of angular misalignment are rather complicated and the direction of angular misalignment turns out to be a key influencing factor.

scholarly journals Study on the Thermal Distribution Characteristics of High-Speed and Light-Load Rolling Bearing Considering Skidding

2018 ◽  
Vol 8 (9) ◽  
pp. 1593 ◽  
Author(s):  
Junning Li ◽  
Jiafan Xue ◽  
Zhitao Ma
Keyword(s):  
Temperature Distribution ◽  
Power Loss ◽  
High Speed ◽  
Roller Bearing ◽  
Transient Temperature ◽  
Rolling Bearings ◽  
Slip Ratio ◽  
Friction Power ◽  
Thermal Distribution ◽  
Light Load

Skidding, which frequently occurs in high-speed rolling bearings, has a significant effect on the thermal distribution and service reliability of the bearings. An improved theoretical model of friction power loss distribution in high-speed and light-load rolling bearings (HSLLRBs) considering skidding is established, and the effects of various operating parameters on the friction power loss are investigated. The results show that the friction power loss of the inner ring and outer ring as well as the total friction power loss of the bearing increase as the slip ratio increases, but that the friction power loss of the cage guide surface and roller oil churning show a reverse trend. In addition, the increase in inner ring speed and kinematic viscosity leads to an increase in bearing friction power loss. The steady and transient temperature field distribution of HSLLRBs is obtained by the finite element method (FEM), and the results show that the inner ring raceway has the highest temperature, whereas the cage has the lowest. The temperature distribution test rig of a full-size roller bearing is constructed, and the influence mechanism of the slip ratio, rotation speed, load, lubrication, and surface topography on the bearing temperature distribution are obtained. The experimental results are consistent with the theoretical results, which also validates the theoretical method.

Reducing Gear Windage Losses From High Speed Gears and Applying These Principles to Actual Running Hardware

2013 ◽  
Author(s):  
Don D. Winfree
Keyword(s):  
Complex Systems ◽  
Power Loss ◽  
High Speed ◽  
Total Power ◽  
Trial And Error ◽  
Test Rig ◽  
Cost Overruns ◽  
Basic Set ◽  
Drive Trains ◽  
Reducing Gear

Windage losses in gearboxes account for a large portion of the total power loss in high-speed drive trains. Very little actual data has been collected specifically quantifying these losses. Traditional techniques to measure the effects of baffles in high speed gearing applications have been done by trial and error on very complex systems. This trial and error technique is used throughout the gearing industry to solve problems without isolating each individual gear windage effect. These solutions are usually sub-optimum. They cause time-consuming delays and cost overruns in many programs. This paper describes two gear baffle test rigs that were built to quantify and minimize the gear windage losses in high-speed drive trains. The intent of the first gearbox baffle test rig was to isolate and measure the windage effects on a single high-speed bevel gear with various baffle configurations. The results of these tests were used to define a basic set of ground rules for designing baffles. This set of ground rules was then applied to another rig replicating the F-35 Liftfan gear box configuration. Immediate benefits were seen. Without this work Lockheed Martin’s X-35 STOVL aircraft would not have been able to operate.

Analysis of High-Speed Cylindrical Roller Bearing With Flexible Rings Mounted in a Squeeze Film Damper

2007 ◽  
Author(s):  
Cyril Defaye ◽  
Daniel Nelias ◽  
Florence Bon
Keyword(s):  
Gas Turbine ◽  
Load Distribution ◽  
High Speed ◽  
Roller Bearing ◽  
Squeeze Film ◽  
Turbine Engines ◽  
Radial Clearance ◽  
Elastic Coupling ◽  
Gas Turbine Engines ◽  
Squeeze Film Damper

For high-precision mechanical systems such as gas-turbine engines, which operate under extreme conditions, it is particularly important to accurately predict the behavior of the mainshaft rolling bearings. This prediction includes, among others, the load distribution, stiffness and power dissipation. Although shaft speeds tend to increase, rings and shaft walls are becoming thinner due to size and weight constraints. Thus, bearing behavior is no longer independent of the housing and ring stiffness. Furthermore, since forty years, the use of squeeze film damper is largely widespread in gas-turbine engines to significantly reduce the vibratory levels. Due to the flexibility of the ring providing the interface between the roller bearing and the fluid film, it appears an elastic coupling which modifies the behavior of the bearing-squeeze film damper system. This paper presents first a squeeze film damper model with a flexible inner ring (i.e. outer ring of the roller bearing). An analytical stop model is introduced to reproduce the interference between the inner ring of the squeeze film damper and its housing. In a second part, an elastic coupling between the presented squeeze film damper model and an existing roller bearing model is proposed. Finally, the results presented show that this coupling has a first order influence on the behavior of the bearing-squeeze film damper system. It is also shown that the coupling between a roller bearing and a squeeze film damper when linked by a flexible ring introduces a dissymmetry of the load distribution with respect to the applied load direction. Moreover, in certain cases, the position of the bearing in its housing can reach eccentricities larger than the radial clearance of the squeeze film damper.

Analysis of a Planet Bearing in a Gear Transmission System

1976 ◽  
Vol 98 (1) ◽  
pp. 40-46 ◽  
Author(s):  
J. Y. Liu ◽  
Y. P. Chiu
Keyword(s):  
Load Distribution ◽  
High Speed ◽  
Roller Bearing ◽  
Arbitrary System ◽  
Inertial Forces ◽  
Elastic Ring ◽  
Gear Transmission System ◽  
Bearing Load ◽  
Planet Gear ◽  
Thin Elastic Ring

This paper develops a general theory whereby the effects of the elastic distortions of a planet bearing outer ring due to gear loads and inertial forces on the bearing load distribution and fatigue life can be considered. The analysis makes use of a recently developed solution for a thin elastic ring under an arbitrary system of loads. A numerical example for a planet gear roller bearing under heavy gear loads and operating at a high speed is presented.

Heat Generation of Bearing

2011 ◽  
Vol 480-481 ◽  
pp. 962-967 ◽  
Author(s):  
Yan Shuang Wang ◽  
Zhe Liu ◽  
Hai Feng Zhu
Keyword(s):  
Heat Generation ◽  
Power Loss ◽  
Integral Method ◽  
High Speed ◽  
Ball Bearing ◽  
High Reliability ◽  
Roller Bearing ◽  
Rolling Bearing ◽  
Heat Sources ◽  
Local Method

Heat generation of a bearing was studied based in this paper. Computational models of power loss were built. The total heat generation was gotten. Influences on total heating were analyzed at various inner ring rolling velocities and applied loads. The results show that bearing rolling velocity and axial load affect heat generation strongly. Meanwhile sliding friction, which exists between balls and the cage pocket, cages and the surface of outer ring, is the main factors of bearing heating. Bearings with shaft are mainly used in gyro motors of aviation, aerospace, marine navigational systems, which own a long life and high reliability. Heat generated by friction affects its performance, life and reliability, and consequently influences control precision and life of gyro motors. If the rate of heat dissipation is less than the rate of the heat generation, the system temperatures will raise, the hardness of bearing ring and rolling element steel decrease, and resulting in plastic deformations, lubricant deterioration occurs, ultimately, heat imbalance failure leads to breakage of bearing components and bearing seizure[1,2].So precise evaluating heat generation of bearings with shaft is important for design, manufacture and application of bearing. The heat generation of bearing comes from power loss of friction. The traditional methods contain the local method and integral method [3]. Palmgren who used the integral method based on experimental results advanced an empirical formula of total friction moment [4]. The calculation result is lower than the fact because ignoring infection of lubricant flux. Astringe and Smith improved the above formula .But it was just for roller bearing. Harris established a local method for the ball bearing and rolling bearing [5]. Pouly et al [6, 7] analyzed part power loss of the high speed rolling bearing based on local method. Compared with the integral method, the local method calculated heating of all heat sources. The results were more accurate. Liu Zhi-quan, Han Min-zheng et al computed the heat of high speed rolling and ball bearing by the local method [8, 9]. This paper studies heat generation mechanism of bearing with shaft from a gyro motor. Different heat sources from bearings are calculated by a self-made program. All factors which influence heat generation would be gotten by analyzing at different working conditions. It would offer a theoretical basis for optimal design and proper use of bearings with shaft.

scholarly journals Lubrication of High-Speed, Large Bore Tapered-Roller Bearings

1978 ◽  
Vol 100 (1) ◽  
pp. 31-38 ◽  
Author(s):  
R. J. Parker ◽  
H. R. Signer
Keyword(s):  
Flow Rate ◽  
Power Loss ◽  
High Speed ◽  
Roller Bearing ◽  
Inlet Temperature ◽  
Shaft Speed ◽  
Roller Bearings ◽  
Lubricant Flow ◽  
Tapered Roller ◽  
Tapered Roller Bearings

The performance of 120.65-mm- (4.75-in.-) bore tapered-roller bearings was investigated at shaft speeds up to 15,000 rpm (1.81 × 106 DN). Temperature distribution and bearing heat generation were determined as a function of shaft speed, radial and thrust loads, lubricant flow rate, and lubricant inlet temperature. Lubricant was supplied either by jets or by a combination of holes through the cone directly to the cone-rib contact and jets at the roller small-end side. Cone-rib lubrication significantly improved high-speed tapered-roller bearing performance, yielding lower cone-face temperatures and lower power loss and allowing lower lubricant flow rates for a given speed condition. Bearing temperatures increased with increased shaft speed and decreased with increased lubricant flow rate. Bearing power loss increased with increased shaft speed and increased lubricant flow rate.

EHL film thickness and load dependent power loss of cycloid reducers

2015 ◽  
Vol 230 (7-8) ◽  
pp. 1303-1317 ◽  
Author(s):  
Athanassios Mihailidis ◽  
Emmanouil Athanasopoulos ◽  
Konstantinos Agouridas
Keyword(s):  
Film Thickness ◽  
Load Distribution ◽  
Power Loss ◽  
High Efficiency ◽  
Distribution Model ◽  
Total Power ◽  
Loss Minimization ◽  
Robotic Arms ◽  
Contact Points ◽  
High Reduction

Robotic arms, space joints and micro-medical devices demand high positioning accuracy, high efficiency, lightweight reducers which often are required to be lubricated for life. Cycloid drives have been gaining popularity in recent years due to their compact form, high reduction ratio and stiffness. Energy loss minimization and ensured good lubrication are vital for those applications. Total power loss is commonly computed as sum of two parts. The first is the zero or minimum-load, which is caused mainly by oil churning and drag as well as contact seals friction. The second part is load dependent and is related to the transmitted power. It is dominated by the friction in all sliding contacts. Geometry parameters of the meshing surfaces affect the load distribution as well as the rolling and sliding velocity of the contacting bodies. The study utilizes meshing equations and an ideal load distribution model to calculate pressure, rolling and sliding at the contacts of a typical 1-disc cycloid reducer. The conditions are characterized by severe slip and counter-turning. A comparison with established EHL models revealed high discrepancy at areas of counter-turning. The ultimate aim of the present study is to calculate the local film thickness and friction. Due to the shortcomings of the aforementioned models, an advanced numerical EHL solver was employed. The determined conditions of the contact points were used as input for the solver. In order to demonstrate the method, calculations were performed for four different load cases as a way of showing the effect of input speed and torque on the efficiency.

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