Application of two-loop transmissions with variator in vehicle transmissions including ones with hybrid powertrain and electric vehicles

Introduction (problem statement and relevance). Increasing the efficiency of transmission and vehicle on the whole remains the relevant objective in the modern automotive industry. One of the ways to solve these tasks can be application of two-loop transmissions with variator in vehicle and electric vehicle transmissions. The two-loop transmissions with variator have a number of characteristic kinematic properties, which are potentially applicable and partially implemented on series units. Application of such transmissions, along with using them within internal combustion engine vehicle propulsion, can be useful in hybrid powertrain vehicle transmissions, which design is subject to the requirements on implementation of matching power paths or flows from the energy sources.
The purpose of the study is analyzing the kinematic or gearing diagrams of the two-loop transmissions, which are used or potentially applicable in the modern vehicle designs. The obtained data on kinematic and load-bearing characteristics will allow comparative assessment of the described designs and obtaining main interrelations of the target parameters with the design features of the transmissions being designed.
Methodology and research methods. A software product is developed that allows obtaining a wide range of transmission characteristics based on the input design parameters, overall dimensions, loads, as well as determining characteristics of the variator used in the two-loop transmissions. The diagrams of dependences given in the paper are graphed on the basis of the data published by the developers of the units, for which the math model contains performed calculation of the main characteristics presented in the form of dimensionless diagrams and intended for visual comparing and determining the main interrelations of the values being simulated.
Scientific novelty and results. Based on the dependencies obtained for two-loop transmissions, the basic interrelations have been formulated allowing to a first approximation to conduct the comparative analysis and monitor the factors causing different useful and negative effects. The results obtained can be used for initial assessment of applicability of the units with similar kinematic diagrams, as well as for illustration of their operation principles. A comparative analysis of the described designs has been conducted in terms of a number of design, kinematic, and load-bearing parameters.
Practical significance. Studies in the field of design of two-loop transmissions with variator can serve as a basis for development of algorithms and software for automated design and calculation of such transmissions, which will significantly reduce the development costs and allow determination of multifactor dependences to ensure efficiency of modern vehicles. The obtained data on characteristics of a number of principal diagrams of two-loop transmissions with variator allow evaluation of effect of their application compared to single-loop transmissions in terms of ensuring the required range, efficiency, kinematic capabilities, and ensuring typical operating modes of transmissions compared to the singleloop transmissions.

1. Van Spijk G.J. Efficient electrification with the pushbelt CVT. CTI magazine, 2018, December, pp. 10–14.

2. Van Spijk G.J. et al. Compact pushbelt variator module to improve energy economy in electrified powertrains. CTI SYMPOSIUM 2019: 18th International Congress and Expo 9–12 December 2019, Berlin, Germany. Springer Berlin Heidelberg, 2021, pp. 523–535.

3. Niii D. et al. Development of new continuously variable transmission for 2.0-liter class vehicles. SAE Technical Paper, 2018, no. 2018-01-1062.

4. Nguyen C.T.P. et al. Dual-motor dual-source high performance EV: a comprehensive review. Energies, 2023, vol. 16, no. 20, p. 7048.

5. Gao Y., Ehsani M. A torque and speed coupling hybrid drivetrain-architecture, control, and simulation. IEEE transactions on power electronics, 2006, vol. 21, no. 3, pp. 741–748.

6. Kwon K., Seo M., Min S. Efficient multi-objective optimization of gear ratios and motor torque distribution for electric vehicles with two-motor and two-speed powertrain system. Applied Energy, 2020, vol. 259, p. 114190.

7. Lin X., Li Y., Zhang G. Bi-objective optimization strategy of energy consumption and shift shock based driving cycle-aware bias coefficients for a novel dualmotor electric vehicle. Energy, 2022, vol. 249, p. 123596.

8. Ge S., Hou S., Yao M. Electromechanical coupling dynamic characteristics of the dual-motor electric drive system of hybrid electric vehicles. Energies, 2023, v. 16, no. 7, p. 3190.

9. Kulikov I.A., Karpukhin K.E., Kurmaev R.Kh., Ivanov V.G. [X-in-the-Loop technology for research and development of electric vehicles]. Trudy NAMI, 2021, no. 2 (285), pp. 6–14. DOI: 10.51187/0135-3152-2021-2-6-14. EDN: DJTJKK. (In Russian)

10. Kurmaev R.Kh., Lepeshkin A.V. [Accuracy enhancement for vehicle motion mathematical model on the basis of test results]. Izvestiya MGTU MAMI, 2009, vol. 1, no. 1, pp. 46–56. EDN: KHRAQJ. (In Russian)

11. Dadashev M.D., Shcherbaev P.A. [Statistics and trends in the development of passenger electric vehicles, the application of statistical analysis methods in the field of their conceptual design]. Avtomobil’naya promyshlennost’, 2024, no. 4, pp. 4–9. EDN: IGKAHT. (In Russian)

12. Lauinger C. et al. Chain CVT highlights for new energy vehicles. VDI-CVT. Baden-Baden, 2019.

13. Srivastava N., Haque I. Nonlinear dynamics of a friction-limited drive: application to a chain continuously variable transmission (CVT) system. Journal of Sound and Vibration, 2009, vol. 321, no. 1-2, pp. 319–341.

14. Do H., Oh S. CVT for a small electric vehicle using centrifugal belt pulley. Energies, 2022, vol. 15, no. 23, pp. 8800.

15. Perodua Ativa – how D-CVT is different to other CVTs. Available at: https://paultan.org/2021/02/24/perodua-ativa-how-d-cvt-is-different-to-other-cvts (accessed 21 October 2024).

16. Van der Sluis F. et al. The CVT pushbelt reinvented for future compact and efficient powertrains. Proceedings of the 2017 JSAE Annual Congress, Yokohama, Japan, 2017, pp. 24–26.