摘要:
A piezoelectric actuating drive is calibrated so that displacements or movements of its actuator output beam (4) become independent of environmental operating conditions and of piezoelectric instabilities. For this purpose an automatic determination and correlating of energizing signal values and respective displacement positions of an actuator beam (4) are performed on the basis of first sensing or measuring striking times (t1, t2) when the actuator beam (4) encounters at least one, preferably two limit stops which limit the beam displacement caused by piezoelectric action. The change of the electric capacitance of a piezostack (3) that displaces the actuator output beam (4) is measured when the beam (4) strikes a limit stop. Instead of measuring a change in the electric capacitance of the piezostack (3), electric charge impulses may be measured at the time (t1, t2) and evaluated for the correlation between the energizing control or input signal and the corresponding output beam displacement. The correlation or calibration is performed automatically by an electronic signal processing circuit when such calibration is desired in response to an operator input or it is performed automatically in response to a control program stored in a memory of the electronic signal processing circuit.
摘要:
A mechanical resonator has an electronically adjustable resonance frequency and is especially adapted to be used as a tunable vibration absorber. The mechanical resonator includes an inertial mass mounted on a free end of a spring, which is secured at its other end to the structure that is to be vibrationally damped. In order to vary the resonant frequency of the resonator, an electromechanical converter such as a piezoelectric element is connected to the spring and/or the inertial mass, and a displacement and/or acceleration sensor provides a sensor signal that is dependent on the respective displacement and/or acceleration of the spring and/or the inertial mass. An electronic control circuit generates an actuating signal based on the sensor signal. The actuating signal is applied to the electro-mechanical converter, which responsively exerts an adjusting force onto the spring and/or the inertial mass. The control circuit may include one or more variable amplifiers, inverters, and phase shifters, to control the actuating signal such that the adjusting force exerted by the electromechanical converter either counteracts or reinforces the bending force exerted by the inertial mass on the spring. In this manner, the effective total spring constant of the resonator can be increased or decreased relative to the inherent spring constant of the spring, whereby the resonant frequency is adjusted.
摘要:
A piezoelectric actuator or sensor includes a solid state body made of a monolithic piezoelectric material, a plurality of actuating electrodes formed as closed-loop electrodes entirely around the perimeter of the solid state body, and a support plate with two contact electrodes respectively having interdigitally intermeshing contact fingers arranged thereon. The intermeshing or alternating contact fingers of the two contact electrodes respectively contact alternating ones of the actuating electrodes, preferably through an adhesive layer having conducting particles dispersed therein. The energized actuating electrodes effectively form virtual piezoelectric layers in the solid state body.
摘要:
A deformable aerodynamic profiled member has a front profile area and a rear profile area in the outflow area. It is bounded by shells on the pressure side and/or on the suction side, converging in a rear profile edge (6). D33 piezo actuators are provided in at least some locations for deformation of the profiled member. The piezo actuators are aligned such that their length changes essentially in the direction of the planes of the shells when acted upon by electricity.
摘要:
A ligand layer on a metal surface is capable of being reversibly switched between adhesion and deadhesion. The ligand layer includes substituted pyridine dimers and/or pyridine trimers which are selected from the group consisting of: with R1 through R6 being able to be equal or different and being selected from the group consisting of —R—CH(O)CH2, OH, —O—R, NR2, NHR, NH2, CO2H, CO2R, R and H. R is selected from the group consisting of alkyl and aryl residues with the proviso that not all residues R1 through R6 are hydrogen atoms at the same time. R7 is selected from the group consisting of —R—CH(O)CH2, OH, —O—R, NR2, NHR, NH2, CO2H, CO2R, CONHR, R and H, with R being selected from the group consisting of alkyl and aryl residues. Y is selected from the group consisting of silicon, carbon, nitrogen, phosphorus and oxygen atoms, and X is an oxygen, sulfur or phosphorus atom, and n having the value 0 or 1.
摘要:
An electrostrictive or piezoelectric actuator device includes a solid state actuator element (4) that is elongated in the lengthwise direction (L) and contracted in the transverse direction (T) upon application of an electric voltage thereto. The actuator element (4) is clampingly held between a housing floor and an actuator output pin (6) in a housing (2). A protective interlayer (12) is respectively arranged between the lengthwise end faces of the actuator element (4) and the housing floor and the actuator pin respectively, to protect the actuator element against transverse stress peaks. The interlayer (12) provides a soft or elastic coupling in the transverse direction and a substantially rigid, force and stroke transmitting coupling in the lengthwise direction. To achieve this, each interlayer (12) is made of a material having an anisotropic modulus of elasticity with a lengthwise stiffness that is considerably higher than that of the solid state material of the actuator element and a transverse stiffness that is less than that of the solid state material of the actuator element.
摘要:
The invention relates to an electro-hydraulic actuator, especially for an antilock brake system, which directly converts electrical input energy into hydraulic useful energy and has an especially simple and problem-free design as well as very rapid adjustability. A working chamber of the actuator according to the invention is filled with an electrostrictive fluid and provided with an electrically controlled electrode system to generate an electrical field that causes a change in pressure and/or volume in the electrostrictive fluid.
摘要:
The invention relates to a linear, hydraulic pivot drive, especially for the flap control system of aerodynamic structures. Said pivot drive comprises a housing provided with ports for introducing a hydraulic medium, a piston which is arranged inside the housing and can be axially displaced by the effect of the hydraulic medium, and an output shaft which is provided with coarse threads and interacts with the piston in order to cover the axial displacement of the piston into a rotational movement. The invention is characterized in that the output shaft is integrated into the piston, the coarse threads running in the same direction and engaging in the piston, and the cross-section of the piston has a spline profile for effectively preventing a rotational movement of the piston.
摘要:
A piezoelectric actuating device for controlling a flap on a rotor blade of a helicopter includes a piezo element arrangement including at least one piezoelectric stack actuator. A power transmission frame is coupled to the piezo element arrangement, the power transmission frame including an abutment and a driven element and generating a force therebetween from a change in length of the piezo element arrangement upon an excitation thereof, the force acting transversely to a direction of a centrifugal force of the rotor blade. A first holding device is provided including a pair of first flexible straps configured to fix the power transmission frame relative to the rotor blade in the direction of the centrifugal force and to allow the power transmission frame to move relative to the rotor blade transversely to the direction of the centrifugal force within a limited range. A second holding device is provided including a pair of second flexible straps configured to fix the abutment relative to the rotor blade transversely to the direction of the centrifugal force and to allow the abutment to move relative to the rotor blade in the direction of the centrifugal force within a limited range.
摘要:
An aerodynamic component such as a helicopter rotor blade has an aerodynamic flow profile, a free end and a mounting end forming a blade root for attachment to a rotor mast. A blade section between the root and the free end has a leading edge and a trailing edge as viewed in the flow or chord direction. The blade is enclosed on its suction side and its pressure side with a respective skin. A nose flap or leading edge flap is secured to the leading edge by a bearing or hinge. The blade tilting angle is adjustable by piezo-drive elements arranged in at least one pair forming an actuator for each nose flap. The piezo-elements of a pair are arranged in the chord direction one behind the other and the pair is secured to the body of the blade by a fixed point positioned between the elements of a pair. The expansion and contraction from the piezo-element closer to the trailing edge is transmitted to the flap by a push rod. The expansion and contraction of the piezo-element closer to the leading edge is transmitted to the flap by a pronged pull-fork. The push rod and the pull-fork drive a free end of a lever secured to the flap, whereby a displacement of the push rod or of the pull fork causes the tilting adjustment of the flap by a push-pull action.