Structure and inner electrical connection

A piezo element is an electromechanical converter. The piezo element is a type of ceramic that converts electrical energy directly into mechanical energy (power/travel). The piezo element expands when voltage is applied. This creates the stroke of the nozzle needle. To achieve a greater stroke, a piezo element can be structured in a number of layers.

Fig 1: Injection System - Circuit Diagram

Courtesy of BMW OF NORTH AMERICA, INC.