Toyota Electronic Modulated Suspension
HOW TEMS WORKS
The system uses a closed loop of piezoelectric ceramic sensors and actuators to continually monitor the suspension vibration arising from road roughness. The sensor produces a voltage which is amplified, altered in phase, and applied to the 88-element piezoelectric actuator. The actuator produces .50µmdisplacement which is hydraulically amplified to 2mmand which is sufficient to adjust the dampingforce in the shock absorber system from firm to soft within .20 milliseconds.
The shock absorber of suspension has two important basic functions.
One is to control vehicle attitude changes when steering and when accelerating and decelerating, and the other is to dampen forces transmitted from the road by its damping effect, thus softening shocks. The characteristics of these two demands in performance, driving stability and riding comfort, conflict with each other but are selected from the concept of a car and from coaching by users. Namely, someone puts stress on driving stability and the other puts stress on riding comfort. Electronics have advanced in recent years and the use of electronic absorber control systems in order to achieve both driving stability and riding comfort has become widespread first of all in Japanese vehicles and also in European and American vehicles.
Toyota first developed its TEMS (Toyota Electronic Modulated Suspension) in 1983 and since then many improvements have been added.
This time we have put to practical use electronic control suspension (TEMS) that uses wheel stroke sensors.
By developing this system, not only have we introduced effective control logic but we have also used an intelligent power MOSFET module newly developed for the control unit.
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