scholarly journals A novel bicycle rear hub transmission with a magnetic gear mechanism

2018 ◽  
Vol 10 (7) ◽  
pp. 168781401878482 ◽  
Author(s):  
Yi-Chang Wu ◽  
Chin-Tsung Chan
Keyword(s):  
High Speed ◽  
Power Flow ◽  
Flow Path ◽  
Gear Train ◽  
Magnetic Flux Density ◽  
Speed Ratio ◽  
Direct Drive ◽  
Kinematic Equation ◽  
Gear Mechanism ◽  
Magnetic Gear

This article proposes a new magnetic rear hub transmission for bicycles, which consists of a coaxial magnetic gear mechanism to serve as the speed-changing device and a speed control mechanism to govern the gear stage. A 3-speed magnetic hub transmission, including a low-speed gear, a direct-drive gear, and a high-speed gear, is designed and installed in the rear hub of a bicycle, which allows the rider to select different gears to adjust the pedaling force. For a new kind of rear hub transmission, kinematic analysis and power-flow path analysis are essential to validate the speed ratio and the power-flow path at each gear stage. They are also the fundamentals for the mechanical efficiency analysis. Here, a system’s kinematic equation, which is an analytical approach and analogous to the kinematics of a basic planetary gear train, for the presented coaxial magnetic gear mechanism is derived without considering the complex space harmonics of the magnetic flux density distribution presented in previous studies. Hence, the speed ratio at each gear stage of the magnetic hub transmission can be easily calculated.

The Wolfrom Gear Train: A Case of Highest-Complexity Related Modifications of the Tooth Meshing

2009 ◽  
Author(s):  
Kiril Arnaudov ◽  
Dimitar Karaivanov
Keyword(s):  
Design Problem ◽  
High Speed ◽  
Technical Problem ◽  
Gear Train ◽  
Speed Ratio ◽  
Specific Design ◽  
Number Of Teeth

The Wolfrom gear is suitable for high speed ratios with an efficiency which is not optimal, but still acceptable. The version with single-rim satellites has significant design and technological advantages. However, the determination of the most appropriate modification coefficients poses a technical problem as the modifications are now related instead of being chosen independently. The geometrical calculations of the single-rim satellites version are performed in the paper. Speed ratio, number of teeth of the satellites, pressure angles and modification coefficients are determined. Advisable values for these parameters are given. As an example a specific design problem for the replacement of a three-stage planetary reducer (consisting of 15 gears) with a Wolfrom gear train (6 gears) the following calculations were performed.

EMBODIMENT DESIGN OF NOVEL 5-SPEED REAR DRIVE HUBS FOR BICYCLES

2015 ◽  
Vol 39 (3) ◽  
pp. 431-441 ◽  
Author(s):  
Yi-Chang Wu ◽  
Tze-Cheng Wu
Keyword(s):  
Power Flow ◽  
Degrees Of Freedom ◽  
Planetary Gear ◽  
Gear Train ◽  
Main Body ◽  
Direct Drive ◽  
Drive Gear ◽  
Planetary Gear Train ◽  
Embodiment Design ◽  
The Relationship

This paper presents embodiment design of 5-speed rear drive hubs for bicycles. A 7-link, 2-degrees of freedom (DOF) compound planetary gear train as the main body of a rear drive hub is introduced. The relationship between the number of coaxial links of a planetary gear train and the number of gear stages that a drive hub can provide with is discussed. By means of kinematic analysis, four speed ratios of the planetary gear train are derived, which represents four forward gears of the rear drive hub. By adding a direct-drive gear, five forward gears can be provided and two feasible clutching sequence tables are synthesized. Manual translational-type gear-shifting mechanisms are further designed to incorporate with the planetary gear train for appropriately controlling the gear stage. The power-flow path at each gear stage is checked to verify the feasibility of the proposed design. Finally, two novel 5-speed bicycle rear drive hubs are presented.

scholarly journals Design and Analysis of a Novel Speed-Changing Wheel Hub with an Integrated Electric Motor for Electric Bicycles

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Yi-Chang Wu ◽  
Zi-Heng Sun
Keyword(s):  
High Speed ◽  
Power Transmission ◽  
Permanent Magnet Synchronous Motor ◽  
Planetary Gear ◽  
Rear Wheel ◽  
Gear Train ◽  
Direct Drive ◽  
Element Analysis ◽  
Embodiment Design ◽  
Electric Bicycles

The aim of this paper is to present an innovative electromechanical device which integrates a brushless DC (BLDC) hub motor with a speed-changing wheel hub stored on the rear wheel of an electric bicycle. It combines a power source and a speed-changing mechanism to simultaneously provide functions of power generation and transmission for electric bicycles. As part of the proposed integrated device, the wheel hub consists of a basic planetary gear train providing three forward speeds including a low-speed gear, a direct drive, and a high-speed gear. Each gear is manually controlled by the shift control sleeve to selectively engage or disengage four pawl-and-ratchet clutches based on its clutching sequence table. The number of gear teeth of each gear element of the wheel hub is synthesized. The BLDC hub motor is an exterior-rotor-type permanent-magnet synchronous motor. Two-dimensional finite-element analysis (FEA) software is employed to facilitate the motor design and performance analysis. An analysis of the power transmission path at each gear is provided to verify the validity of the proposed design. The results of this work are beneficial to the embodiment, design, and development of novel electromechanical devices for the power and transmission systems of electric bicycles.

DEVELOPMENT OF 3-SPEED REAR HUB BICYCLE TRANSMISSIONS WITH GEAR-SHIFTING MECHANISMS

2015 ◽  
Vol 39 (3) ◽  
pp. 407-418 ◽  
Author(s):  
Yi-Chang Wu ◽  
Che-Wei Chang
Keyword(s):  
Design Process ◽  
Power Flow ◽  
Installation Space ◽  
Speed Ratio ◽  
Systematic Design ◽  
Gear Teeth ◽  
Design Concepts ◽  
Embodiment Design ◽  
Epicyclic Gear ◽  
Gear Mechanism

Rear hub bicycle transmissions require less maintenance and are more reliable than rear derailleurs. This study proposes a systematic design process for the conceptual design of 3-speed rear hub bicycle transmissions. By analyzing the kinematics of a basic epicyclic gear mechanism using the fundamental circuit method, the gear sequence and clutching sequence arrangements for 3-speed rear hub transmissions can be obtained. The numbers of gear-teeth for all gear elements resulting in a minimum installation space and satisfying the required speed ratio at each gear stage are determined. A gear-shifting mechanism is constructed to sequentially control the power-flow path within the epicyclic gear mechanism so as to provide three forward gears. An atlas of 3-speed rear hub bicycle transmissions is listed, where three devices are new design concepts and are suitable for further embodiment design. The results of this study will lead to the creation of new multi-speed rear hub bicycle transmissions.

scholarly journals Analysis of continuously variable transmission for flywheel energy storage systems in vehicular application

2014 ◽  
Vol 229 (2) ◽  
pp. 273-290 ◽  
Author(s):  
Aditya Dhand ◽  
Keith Pullen
Keyword(s):  
Energy Storage ◽  
High Speed ◽  
Power Flow ◽  
Mechanical Energy ◽  
Storage System ◽  
Continuously Variable Transmission ◽  
Speed Ratio ◽  
Flywheel Energy Storage ◽  
Energy Storage Devices ◽  
Variable Transmission

Energy storage devices are an essential part of hybrid and electric vehicles. The most commonly used ones are batteries, ultra capacitors and high speed flywheels. Among these, the flywheel is the only device that keeps the energy stored in the same form as the moving vehicle, i.e. mechanical energy. In order to connect the flywheel with the vehicle drive line, a suitable means is needed which would allow the flywheel to vary its speed continuously, in other words a continuously variable transmission (CVT) is needed. To improve the efficiency and speed ratio range of the variators, a power spilt CVT (PSCVT) can be employed. This paper discusses the kinematics of PSCVT used to connect the flywheel to the driveline. A methodology describing the characteristic equations of speed ratio, power flow and efficiency of the PSCVT for various types including power recirculating and multi regime in both directions of power flow has been presented. An example of a PSCVT for a flywheel energy storage system (FESS) is computed using the derived equations and the results compared.

Kinematic Analysis of an 8-Speed Bicycle Transmission Hub

2013 ◽  
Vol 479-480 ◽  
pp. 234-238 ◽  
Author(s):  
Yi Chang Wu ◽  
Pei Wun Ren ◽  
Li An Chen
Keyword(s):  
Kinematic Analysis ◽  
Power Flow ◽  
Planetary Gear ◽  
Speed Ratio ◽  
Flow Paths ◽  
Gear Teeth ◽  
Gear Mechanism ◽  
Flow Diagrams ◽  
Internal Gear ◽  
Planetary Gear Mechanism

A transmission hub is a speed changing mechanism which is an important device in the transmission system of bicycles. This paper presents the kinematic analysis of an 8-speed bicycle transmission hub by using the fundamental circuit method. First, a distributed-flow type planetary gear mechanism, which consists of two parallel-connected transmission units and one differential unit, and the corresponding clutch sequence table of an 8-speed transmission hub are introduced. Based on the fundamental circuits, four kinematic equations of the transmission hub are derived. Then, the speed ratio of each speed is formulated, which is a function of gear ratios of external and internal gear pairs. By submitting the numbers of gear teeth into these formulas, the value of speed ratio at each speed can be calculated. Finally, the power-flow diagrams at related speeds are presented to illustrate the power-flow paths of the transmission hub.

A kind of magnetic gear with high speed ratio

2010 ◽  
Author(s):  
Yongkui Man ◽  
Yushuang Zhao ◽  
Chunyuan Bian ◽  
Shuangquan Wang ◽  
Hongbin Zhao
Keyword(s):  
High Speed ◽  
Speed Ratio ◽  
Magnetic Gear

Performance analysis of magnetic gear with Halbach array for high power and high speed

2020 ◽  
Vol 64 (1-4) ◽  
pp. 959-967
Author(s):  
Se-Yeong Kim ◽  
Tae-Woo Lee ◽  
Yon-Do Chun ◽  
Do-Kwan Hong
Keyword(s):  
Permanent Magnet ◽  
Eddy Current ◽  
High Power ◽  
High Speed ◽  
Torque Ripple ◽  
Eddy Current Loss ◽  
Element Analysis ◽  
Current Loss ◽  
Halbach Array ◽  
Magnetic Gear

In this study, we propose a non-contact 80 kW, 60,000 rpm coaxial magnetic gear (CMG) model for high speed and high power applications. Two models with the same power but different radial and axial sizes were optimized using response surface methodology. Both models employed a Halbach array to increase torque. Also, an edge fillet was applied to the radial magnetized permanent magnet to reduce torque ripple, and an axial gap was applied to the permanent magnet with a radial gap to reduce eddy current loss. The models were analyzed using 2-D and 3-D finite element analysis. The torque, torque ripple and eddy current loss were compared in both models according to the materials used, including Sm2Co17, NdFeBs (N42SH, N48SH). Also, the structural stability of the pole piece structure was investigated by forced vibration analysis. Critical speed results from rotordynamics analysis are also presented.

scholarly journals Research on Performance Test System of Space Harmonic Reducer in High Vacuum and Low Temperature Environment

Machines ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Jing Wang ◽  
Zhihua Wan ◽  
Zhurong Dong ◽  
Zhengguo Li
Keyword(s):  
Low Temperature ◽  
High Speed ◽  
Performance Test ◽  
High Reliability ◽  
High Vacuum ◽  
Test System ◽  
Low Noise ◽  
Speed Ratio ◽  
Space Harmonic ◽  
Temperature Environment

The harmonic reducer, with its advantages of high precision, low noise, light weight, and high speed ratio, has been widely used in aerospace solar wing deployment mechanisms, antenna pointing mechanisms, robot joints, and other precision transmission fields. Accurately predicting the performance of the harmonic reducer under various application conditions is of great significance to the high reliability and long life of the harmonic reducer. In this paper, a set of automatic harmonic reducer performance test systems is designed. By using the CANOpen bus interface to control the servo motor as the drive motor, through accurately controlling the motor speed and rotation angle, collecting the angle, torque, and current in real time, the life cycle test of space harmonic reducer was carried out in high vacuum and low temperature environment on the ground. Then, the collected data were automatically analyzed and calculated. The test data of the transmission accuracy, backlash, and transmission efficiency of the space harmonic reducer were obtained. It is proven by experiments that the performance data of the harmonic reducer in space work can be more accurately obtained by using the test system mentioned in this paper, which is convenient for further research on related lubricating materials.

scholarly journals Cross-Flow Tidal Turbines with Highly Flexible Blades—Experimental Flow Field Investigations at Strong Fluid–Structure Interactions

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 797
Author(s):  
Stefan Hoerner ◽  
Iring Kösters ◽  
Laure Vignal ◽  
Olivier Cleynen ◽  
Shokoofeh Abbaszadeh ◽  
...  
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Cross Flow ◽  
Speed Ratio ◽  
Fluid Structure Interactions ◽  
Dimensional Parameter ◽  
Fluid Structure ◽  
Passive Flow Control ◽  
Tidal Turbines ◽  
Tidal Turbine

Oscillating hydrofoils were installed in a water tunnel as a surrogate model for a hydrokinetic cross-flow tidal turbine, enabling the study of the effect of flexible blades on the performance of those devices with high ecological potential. The study focuses on a single tip-speed ratio (equal to 2), the key non-dimensional parameter describing the operating point, and solidity (equal to 1.5), quantifying the robustness of the turbine shape. Both parameters are standard values for cross-flow tidal turbines. Those lead to highly dynamic characteristics in the flow field dominated by dynamic stall. The flow field is investigated at the blade level using high-speed particle image velocimetry measurements. Strong fluid–structure interactions lead to significant structural deformations and highly modified flow fields. The flexibility of the blades is shown to significantly reduce the duration of the periodic stall regime; this observation is achieved through systematic comparison of the flow field, with a quantitative evaluation of the degree of chaotic changes in the wake. In this manner, the study provides insights into the mechanisms of the passive flow control achieved through blade flexibility in cross-flow turbines.

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