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Toyota EC-HYMATIC – A New Full Time 4WD System for Automatic Transmission
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English
Abstract
Toyota has developed a new full time 4WD system, called “EC-HYMATIC” or Electronically Controlled - HYdraulic Multi-plate clutch Active Traction Intelligent Control. This system permits an automatic torque transfer, depending on driving conditions, for front and rear wheels under control of the speed difference between the two.
The system developed consists of a center differential, a speed difference control clutch system employing multi-plate clutch, and a gear set for rear axle drive. The speed difference control clutch system is controlled by a unique electro-hydraulic system using a microcomputer. An extensive use of computer simulations and vehicle test and evaluation has successfully developed an appropriate control strategy for the clutch system.
The new 4WD system, EC-HYMATIC, considerably improves handling characteristics, traction performance and stability of a 4WD vehicle.
Authors
Citation
Nakamura, S., Ishikawa, M., Akashi, T., Taniguchi, T. et al., "Toyota EC-HYMATIC – A New Full Time 4WD System for Automatic Transmission," SAE Technical Paper 890526, 1989, https://doi.org/10.4271/890526.Also In
References
- Maretzke J. Richter B. “Directional Control of 4WD Passenger Cars-A Study by Computer Simulation” Paper 861370 SAE Passenger Car Meeting & Exposition Dearborn September 1986
- Muller R. Witte L. “PDS (Porsche Dynamic Slip Control Clutch) - A New Inter- Axle Coupling Device for 4WD-Cars” Paper 880698 SAE International Congress and Exposition Detroit March 1988
- Zomotor A. Leiber H. Neundorf S. Richter K.-H. Buechle K.-H. “Mercedes-Benz 4MATIC, an electronically controlled four-wheel drive system for improved active safety” International Conference on All-Wheel Drive MechE 1986