Adaption of Continuously Variable Transmissions to the Characteristic of a Driven Machine by Bicoupled Planetary Transmissions

1981 ◽  
Vol 103 (1) ◽  
pp. 41-47
Author(s):  
H. W. Mu¨ller
Keyword(s):  
Planetary Gear ◽  
Output Characteristic ◽  
Speed Ratio ◽  
Continuously Variable Transmissions ◽  
Variable Transmission ◽  
Standardized Method ◽  
Ratio Range

Bicoupled Planetary Transmissions composed of any variable Transmission and a planetary gear can be designed to realize any optional speed ratio range including speed reversal and its output characteristic can be approached to the characteristic of the driven machine in order to obtain an economic overall transmission. The paper describes a standardized method to design and to optimize such transmissions.

Effect of the Ratio Spread of CVU in Automotive Kinetic Energy Recovery Systems

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
F. Bottiglione ◽  
G. Mantriota
Keyword(s):  
Kinetic Energy ◽  
Energy Recovery ◽  
High Efficiency ◽  
Fixed Ratio ◽  
Planetary Gear ◽  
Speed Ratio ◽  
Direct Drive ◽  
Performance Indexes ◽  
Continuously Variable Transmissions ◽  
Ratio Spread

The Kinetic Energy Recovery Systems (KERS) are being considered as promising short-range solution to improve the fuel economy of road vehicles. The key element of a mechanical hybrid is a Continuously Variable Unit (CVU), which is used to drive the power from the flywheel to the wheels and vice versa by varying the speed ratio. The performance of the KERS is very much affected by the efficiency of the CVU in both direct and reverse operation, and the ratio spread. However, in real Continuously Variable Transmissions (CVT), the ratio spread is limited (typical value is 6) to keep acceptable efficiency and to minimize wear. Extended range shunted CVT (Power Split CVT or PS-CVT), made of one CVT, one fixed-ratio drive and one planetary gear drive, permit the designer to arrange a CVU with a larger ratio spread than the CVT or to improve its basic efficiency. For these reasons, in the literature they are sometimes addressed as devices for proficient application to KERS. In this paper, two performance indexes have been defined to quantify the effect of the ratio spread of PS-CVT on the energy recovery capabilities and overall round-trip efficiency of KERS. It is found that no substantial benefit is achieved with the use of PS-CVT instead of direct drive CVT, because the extension of the speed ratio range is paid with a loss of efficiency. It is finally discussed if new generation high-efficiency CVTs can change the scenario.

scholarly journals An Experimental Study on Dynamics of a Novel Dual-Belt Continuous Variable Transmission Based on a Newly Developed Test Rig

2015 ◽  
Vol 2015 ◽  
pp. 1-23 ◽  
Author(s):  
Pak Kin Wong ◽  
Zhengchao Xie ◽  
Yueqiao Chen
Keyword(s):  
Experimental Study ◽  
Analytical Model ◽  
Continuous Variable ◽  
Transmission Efficiency ◽  
Speed Ratio ◽  
Test Rig ◽  
Light Load ◽  
Continuous Variable Transmission ◽  
Continuously Variable Transmissions ◽  
Variable Transmission

A novel dual-belt Van Doorne’s continuous variable transmission (DBVCVT) system, which is applicable to heavy-duty vehicles, has been previously proposed by the authors in order to improve the low torque capacity of traditional single-belt CVT. This DBVCVT is a novel design among continuously variable transmissions and is necessary to be prototyped for experimental study, and the analytical dynamic model for this DBVCVT also needs to be experimentally validated. So, this work originally fabricated a prototype of DBVCVT and integrates this prototype to a light-load hardware-in-the-loop test rig by replacing the engine and load equipment with the AC motor and magnetic powder dynamometer. Moreover, with the use of this newly developed test rig, this work implements the experimental study of this DBVCVT for the first time. The comparison of experimental and simulation results validates the previously proposed analytical model for DBVCVT, and some basic characteristics of the DBVCVT in terms of the reliability, speed ratio, and transmission efficiency are also experimentally studied. In all, this developed test rig with the analytical model lays the foundation for further study on this novel DBVCVT.

Experimental Study of Electro-Mechanical Dual Acting Pulley Continuously Variable Transmission Ratio Calibration

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Bambang Supriyo ◽  
Kamarul Baharin Tawi ◽  
Hishamuddin Jamaluddin ◽  
Mohamed Hussein
Keyword(s):  
Experimental Study ◽  
Reference Data ◽  
Continuously Variable Transmission ◽  
Speed Ratio ◽  
Shaft Speed ◽  
Primary Input ◽  
Calibration Process ◽  
Dc Motors ◽  
Variable Transmission ◽  
Ratio Range

This paper presents an experimental study of Electro-mechanical Dual Acting Pulley (EMDAP) Continuously Variable Transmission (CVT) ratio calibration. When there is no slip between belt and pulley sheaves, the CVT ratio will be the same as the geometrical ratio of secondary to primary pulley radii as well as the primary to secondary speed ratio.  In EMDAP CVT system, both primary and secondary DC motors are used to control the primary and secondary axial pulley positions to vary the primary and secondary pulley radii. In this case, the pulley radii can be measured indirectly using axial pulley position sensors. Calibration process is carried out by manually adjusting the geometrical ratio of secondary to primary radii based on measurements of primary and secondary pulley positions and validated with the primary to secondary speed ratio determined from primary (input) and secondary (output) shaft speed measurements for the CVT ratio range of 0.7 to 2.0. The calibration results are recorded and used as reference data for future EMDAP CVT calibration and ratio control developments.

Research on Control Strategy and Experiment of Electronic Mechanical Continuously Variable Transmission

2011 ◽  
Vol 88-89 ◽  
pp. 191-196
Author(s):  
Lei Zhang ◽  
Yan Chun Zhai ◽  
Hai Xin Zhao ◽  
Guan Jin Chen
Keyword(s):  
Control Strategy ◽  
Pid Control ◽  
Hydraulic System ◽  
Control Algorithm ◽  
Continuously Variable Transmission ◽  
Speed Ratio ◽  
Manufacturing Cost ◽  
Speed Governor ◽  
Continuously Variable Transmissions ◽  
Variable Transmission

Nowadays, most of continuously variable transmissions (CVT) adopt hydraulic system to exert pressure on the cone-plate, in order to realize variable speed control. Electronic Mechanical Continuously Variable Transmission (EMCVT) studied in this paper, however, used rolling screw mechanism instead of the energy-hungry hydraulic system. Mechanical speed governor controlled by electro was adopted in EMCVT to regulate speed, which not only reduced the automobile’s fuel consumption, but also brought down the transmission’s manufacturing cost and failure rate obviously. Further study on the ratio control strategy of EMCVT was made and digital PID control algorithm with target ratio tracing was raised. Moreover, an improved PID control algorithm, that was integral separation and differential precession algorithm, was given. Platform experiment of EMCVT was finished, thus, the functionality and rationality of this transmission’s mechanical structure was proved, so was the feasibility and rationality of the speed ratio control strategy.

Radical Innovative CVT Technology: A Transmission Replacement Example

2003 ◽  
Author(s):  
Johannes Jacobus Naude
Keyword(s):  
Mathematical Model ◽  
Planetary Gear ◽  
Continuous Variable ◽  
Manual Transmission ◽  
Mechanical Joint ◽  
Continuous Variable Transmission ◽  
Traction Fluid ◽  
Variable Transmission ◽  
Automated Manual Transmission ◽  
Ratio Range

Currently the automotive CVT (Continuous Variable Transmission) market is dominated by CVT’s that work on a friction drive principle operating in a traction fluid. This paper presents a new CVT concept based on a unique mechanical joint unit. These units are used in parallel as an intermittent drive to produce a CVT. A mathematical model of the mechanical joint is derived and its suitability to operate within the CVT is discussed. The extension of the ratio range of the CVT via a planetary gear arrangement is demonstrated. The integration of the CVT with AMT (Automated Manual Transmission) technology is discussed and an example of such integration is presented. The efficiency of the system is estimated from related published information. In the summary the advantages of the CVT are discussed by comparison to traction fluid based CVT’s.

Design, Modeling, and Experimental Validation of a Novel Infinitely Variable Transmission Based on Scotch Yoke Systems

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
X. F. Wang ◽  
W. D. Zhu
Keyword(s):  
Planetary Gear ◽  
Speed Ratio ◽  
Control Module ◽  
Kinematic Behavior ◽  
Input Control ◽  
Variable Transmission ◽  
Infinitely Variable Transmission ◽  
Planetary Gear Sets ◽  
Noncircular Gears ◽  
Crank Length

A novel infinitely variable transmission (IVT) based on scotch yoke systems is designed to provide a continuously varied output-to-input speed ratio from zero to a specified value. By changing the crank length of scotch yoke systems, the speed ratio of the IVT can be continuously adjusted. The IVT consists of a pair of noncircular gears and two modules: an input-control module and a motion conversion module. The input-control module employs two planetary gear sets to combine the input speed of the IVT with the control speed from the stepper motor that changes the crank length of scotch yoke systems. The motion conversion module employs two scotch yoke systems to convert the combined speeds from the input-control module to translational speeds of yokes, and the translational speeds are converted to output speeds through rack–pinions. The speed ratio between the output of the motion conversion module and the input of the input-control module has a shape of a sinusoidal-like wave, which generates instantaneous variations. Use of scotch yoke systems provides a benefit to isolate the interaction between the crank length and the shape of the speed ratio, and a pair of noncircular gears can be used to eliminate the instantaneous variations of the speed ratio for all crank lengths. A prototype of the IVT was built and instrumented, and its kinematic behavior was experimentally validated. A driving test was conducted to examine the performance of the IVT.

Design, Modeling, and Simulation of a Geared Infinitely Variable Transmission

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
X. F. Wang ◽  
W. D. Zhu
Keyword(s):  
Planetary Gear ◽  
Speed Ratio ◽  
Start Up ◽  
Continuous Output ◽  
Direction Control ◽  
Variable Transmission ◽  
Infinitely Variable Transmission ◽  
Planetary Gear Sets ◽  
Working Principle ◽  
Crank Length

An infinitely variable transmission (IVT) to provide a continuous output-to-input speed ratio from zero to a certain value is designed, and its working principle is illustrated. It is a geared IVT (GIVT), since its function to achieve the continuously varied speed ratio is implemented by gears. Crank-slider systems are used in the GIVT; the output-to-input speed ratio is changed with the crank length. Racks and pinions, whose motion is controlled by planetary gear sets, are used to change the crank length when the cranks rotate. One-way bearings are used to rectify output speeds from different crank-slider systems to obtain the output speed of the GIVT. Since the crank-slider systems can introduce variations of the instantaneous speed ratio, a pair of noncircular gears is designed to minimize the variations. A direction control system is also designed for the GIVT using planetary gear sets. Finally, a vehicle start-up simulation and a wind turbine simulation to maintain a constant generator speed are developed based on a GIVT module in the Matlab Simulink environment.

Kinematic considerations for reducing the circulating power effects in gear-type continuously variable transmissions

1998 ◽  
Vol 212 (6) ◽  
pp. 463-478 ◽  
Author(s):  
D Dooner ◽  
H-D Yoon ◽  
A Seireg
Keyword(s):  
Output Power ◽  
Characteristic Curve ◽  
Gear Ratio ◽  
Design Parameters ◽  
Analysis And Design ◽  
Design Considerations ◽  
Maximum Value ◽  
Continuously Variable Transmissions ◽  
Variable Transmission ◽  
Ratio Range

The present study deals with the kinematic analysis and design considerations of a continuously variable transmission (CVT) utilizing non-circular gear (NCG) sets with phase shift and summing differentials. The kinematic relationships are developed with emphasis on the effect of the different design parameters on reducing the circulating power inherent in this type of system. The study shows that a compromise has to be made between the number of non-circular gear sets to be used and the circulating power generated in the system. For the illustrative example of a 200 hp (149 kW) system it is shown that, for a gear ratio range from 1 to 4 and the considered characteristic curve on the non-circular gears, four sets of summing differentials are estimated to be required and the maximum instantaneous circulating power at the worst condition would be approximately 6 times the output power. The circulating power changes from its minimum of 1.5 to its maximum value with an average circulating power of 2.8 times the output power.

scholarly journals Co-Design of CVT-Based Electric Vehicles

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1825
Author(s):  
Caiyang Wei ◽  
Theo Hofman ◽  
Esin Ilhan Caarls
Keyword(s):  
Cooling System ◽  
Design Method ◽  
Low Cost ◽  
Cost Effective ◽  
Speed Ratio ◽  
Air Flow Rate ◽  
Cost Of Ownership ◽  
Variable Transmission ◽  
Primary Focus ◽  
Design Freedom

For an electric vehicle (EV) with a continuously variable transmission (CVT), a novel convex programming (CP)-based co-design method is proposed to minimize the total-cost-of-ownership (TCO). The integration of the electric machine (EM) and the CVT is the primary focus. The optimized system with co-design reduces the TCO by around 5.9% compared to a non-optimized CVT-based EV (based on off-the-shelf components) and by around 2% compared to the EV equipped with a single-speed transmission (SST). By taking advantage of the control and design freedom provided by the CVT, the optimal CVT, EM and battery sizes are found to reduce the system cost. It simultaneously finds the optimal CVT speed ratio and air-flow rate of the cooling system reducing the energy consumption. The strength of co-design is highlighted by comparing to a sequential design, and insights into the design of a low-power EV that is energy-efficient and cost-effective for urban driving are provided. A highly integrated EM-CVT system, which is efficient, low-cost and lightweight, can be expected for future EV applications.

Development of 2 Stage CVT Shift Control Algorithm to Reduce Torque Variation During 1-2 Upshift of Planetary Gear

2012 ◽  
Author(s):  
Jeongman Park ◽  
Sunghyun Ahn ◽  
Oheun Kwon ◽  
Youngho Jun ◽  
Minhyo Kim ◽  
...  
Keyword(s):  
Control Algorithm ◽  
Planetary Gear ◽  
Gear Ratio ◽  
Shift Quality ◽  
Response Characteristics ◽  
Shift Control ◽  
Variable Transmission ◽  
Vehicle Simulator ◽  
Simulation Results ◽  
Fuzzy Control Algorithm

In this paper, a 2 stage continuously variable transmission (CVT) shift control algorithm is proposed for the 1–2 upshift of the planetary gear to achieve the shift quality. A fuzzy control algorithm is designed considering the relatively slower response characteristics of CVT. In order to evaluate the performance of the control algorithm, a 2 stage CVT vehicle simulator is developed including a dynamic model of the CVT powertrain. From the simulation results, it is found that CVT gear ratio changes faster in the inertia phase and remains constant after the inertia phase of the planetary gear shift, which provides the reduced torque variation by the proposed control algorithm.

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