In recent years, the demand for piezoceramic actuators (piezo actuators) has grown significantly due to their increasing use, e.g. in the latest diesel injection systems in the automobile industry. This demand likewise promotes the development of piezo actuators. In many new injection configurations, the piezo actuators are completely surrounded by diesel fuel. This type of configuration of the injection systems is also known as “wet design”.
Since the piezo actuators are chemically and electrically attacked when in direct contact with diesel fuel, which is impure or has been modified by additives, an appropriate protective envelope must be provided for the piezo actuator. This protective envelope should provide both electrical insulation against possible short circuit through the electrically conductive fuel and chemical insulation against the attack of the surrounding fuel on the components of the piezo actuator.
The prior art discloses metal casings of different configurations which surround the piezo actuator. One example of such a metal casing is a corrugated pipe. The metal casings are filled with suitable filler materials in order to effect a transfer of the pressure, which is applied by the fuel, onto the internally situated piezo actuator. However, this design solution has the disadvantages that it is expensive to produce and is space-intensive.
USPTO Backgrounds
USPTO Backgrounds