Abstract: A casing for encapsulation of an electrical component, for example a piezoelectric actuator, comprising an outer layer of a semipermeable material and an inner layer comprising a chemically active, hydrophilic substance that chemically combines with water to form a compound.

Abstract: A piezoelectric actuator comprising a stack of piezoelectric layers formed from a piezoelectric material, a plurality of internal electrodes disposed throughout the stack to define active regions of the piezoelectric material therebetween which are responsive to a voltage applied across two or more groups of the internal electrodes in use, an insulating arrangement which at least partially covers at least one surface of the stack to define a piezoelectric/insulator interface, and two or more side electrodes to connect with the two or more groups of the internal electrodes.

Abstract: A method of poling a ferroelectric sample suitable for use in a fuel injector of an internal combustion engine, the method comprising providing a ferroelectric sample having a stack of ferroelectric layers, wherein adjacent layers are separated by internal electrodes, forming a first group and a second group of electrodes; applying a multiaxial pressure to the ferroelectric sample; and generating an electric field between the first and second group of electrodes to pole the ferroelectric sample. The multiaxial pressure is ideally applied by means of a fluid, and the fluid may be an dielectric fluid or fuel.

Abstract: Piezoelectric actuators of the type comprising a stack of layers of ferroelectric material and intervening electrodes which extend only part-way across the adjacent ferroelectric layers suffer differential remanent stress when electric fields are applied across the layers. To overcome this, a tensile stress is applied to the actuator along an axis substantially perpendicular to the layers of piezoelectric material in the actuator, which tensile stress is sufficient to mechanically align the dipoles, thus giving rise to a remanent strain which is uniform throughout the actuator. The actuator is advantageously heated while the tensile stress is applied, so as to increase the difference between the tensile strength of the material and the applied tensile stress. An alternative arrangement involves subjecting the actuator to a multidirectional stress and reducing the stress along the axis substantially perpendicular to the layers of piezoelectric material in the actuator.

Abstract: An actuator arrangement comprising a piezoelectric actuator having a body section, a shroud which enshrouds at least part of the body section of the actuator, and at least one constrictive member disposed externally with respect to the shroud. The constrictive member applies a constrictive force to the shroud to maintain a seal between the shroud and the underlying body section of the actuator.

Abstract: A casing for encapsulation of an electrical component, for example a piezoelectric actuator, comprising an outer layer of a semipermeable material and an inner layer comprising a chemically active, hydrophilic substance that chemically combines with water to form a compound.

Abstract: A method of operating a fuel injector including a piezoelectric actuator having a stack of piezoelectric elements, comprises applying a discharge current (IDISCHARGE) to the actuator for a discharge period so to discharge the stack from a first differential voltage level across the stack to a second, lower differential voltage level across the stack so as to initiate an injection event, and applying a charge current (ICHARGE) to the actuator for a charge period (T3 to T4?) so as to charge the stack from the second differential voltage level to a third differential voltage level so as to terminate the injection event. The method includes determining at least one engine parameter (e.g. common rail pressure) of the injection event prior to applying the charge current (ICHARGE) to the actuator and selecting the third differential voltage level in dependence on the at least one engine parameter.

Abstract: A method of operating a fuel injector including a piezoelectric actuator having a stack of piezoelectric elements, comprises applying a discharge current (IDISCHARGE) to the actuator for a discharge period so to discharge the stack from a first differential voltage level across the stack to a second, lower differential voltage level across the stack so as to initiate an injection event, and applying a charge current (ICHARGE) to the actuator for a charge period (T3 to T4?) so as to charge the stack from the second differential voltage level to a third differential voltage level so as to terminate the injection event. The method includes determining at least one engine parameter (e.g. common rail pressure) of the injection event prior to applying the charge current (ICHARGE) to the actuator and selecting the third differential voltage level in dependence on the at least one engine parameter.

Abstract: a piezoactuator having at least one outer surface comprises a multilayer structure of at least one piezoelectric ceramic layer and at least two electrodes, with the at least one outer surface of the piezoactuator being coated with a passivation material.

Abstract: A piezoelectric actuator comprising a stack of piezoelectric layers formed from a piezoelectric material, a plurality of internal electrodes disposed throughout the stack to define active regions of the piezoelectric material therebetween which are responsive to a voltage applied across two or more groups of the internal electrodes in use, an insulating arrangement which at least partially covers at least one surface of the stack to define a piezoelectric/insulator interface, and two or more side electrodes to connect with the two or more groups of the internal electrodes.

Abstract: A method for the determination of the arrangement of electrodes in the manufacture of a piezoelectric component, in particular of a piezoactuator, comprises the steps of making available of a base body consisting of a multilayer structure of at least one piezoelectric ceramic layer and at least two electrodes, wherein the base body has at least two outer surfaces and at least one electrode extends at least regionally up to at least one of the outer surfaces and is exposed at one end there, whereas the at least two electrodes on at least one further outer surface are not exposed, and removal of the material from the outer surface on which the electrodes are not exposed, using an electrically conductive stripper, wherein, on the removal of the material from the one outer surface, an electrical voltage is applied between the stripper, which is adapted so as to facilitate the removal of the material and at least one electrode and the electrical current flowing through the at least one electrode on the removal of

Abstract: An actuator arrangement comprising a piezoelectric actuator having a body section, a shroud which enshrouds at least part of the body section of the actuator, and at least one constrictive member disposed externally with respect to the shroud. The constrictive member applies a constrictive force to the shroud to maintain a seal between the shroud and the underlying body section of the actuator.

Abstract: A method of poling a ferroelectric sample suitable for use in a fuel injector of an internal combustion engine, the method comprising providing a ferroelectric sample having a stack of ferroelectric layers, wherein adjacent layers are separated by internal electrodes, forming a first group and a second group of electrodes; applying a multiaxial pressure to the ferroelectric sample; and generating an electric field between the first and second group of electrodes to pole the ferroelectric sample. The multiaxial pressure is ideally applied by means of a fluid, and the fluid may be an dielectric fluid or fuel.

Abstract: The invention relates to a method for the monitoring and evaluation of the operation of a piezoelectric actuator, wherein electrical discharging and charging processes of the actuator are monitored and the operation of the actuator is evaluated with reference to the time course of the discharging and charging processes. The invention further relates to an apparatus for the carrying out of the method.

Abstract: A method of poling a ferroelectric sample (14) of the type suitable for use in an actuator for an injection arrangement comprises the steps of providing a sample of ferroelectric material having first and second opposing end faces (23), first and second opposing side faces (21), and a stack of ferroelectric layers (16), wherein adjacent layers are separated from one another by internal electrodes (18a, 18b) arranged substantially parallel to the end faces (23) of the sample (14), and applying a primary external electrode arrangement (24a, 24b) to the first and second end faces (23) of the sample (14). A primary poling voltage is applied to the primary electrode arrangement (24a, 24b) so as to polarise substantially the entire ferroelectric sample along a single, first polarisation axis in a first polarisation direction.