TDK Announces Large-displacement Piezoelectric Actuator for Engine Injectors

Aug 29, 2014
Naoshige Shimizu, Nikkei Automotive Technology
The new piezoelectric actuator
The new piezoelectric actuator
[Click to enlarge image]

TDK Corp announced Aug 26, 2014, that it has developed a piezoelectric actuator whose displacement is 20% larger than that of its previous piezoelectric actuator.

It can be used for the injectors of diesel and gasoline engines. Because copper (Cu) electrodes are used between stacked piezoelectric elements, the cost of the new piezoelectric actuator can be low. It was developed by Germany-based Epcos AG, a subsidiary of TDK.

In general, piezoelectric actuators for the injectors of engines use an alloy of silver (Ag) and palladium (Pd) for their electrodes between piezoelectric elements so that it becomes possible to easily extend product life and increase displacement. But Pd is relatively expensive.

TDK reduced the cost of piezoelectric actuator by developing a technology to use Cu, which is inexpensive. However, with Cu electrodes, the amount of displacement tends to be small at the time of applying a voltage. This time, the company used Cu electrodes and realized the amount of displacement equivalent to that with Ag/Pd electrodes by, for example, adding a new material to PZT (lead zirconate titanate), which is a common material for piezoelectric elements.

With regard to the durability of the piezoelectric actuator, TDK achieved one billion cycles in an environment with a temperature of 170°C and an environment with a temperature of 85°C and humidity of 85%. The specifications of the actuator including its displacement can be changed in response to customer requests.