Piezo Actuator Bidirectional Force via Adjustment Element
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Solution Overview
Problem
Existing piezo actuators with multiple elements can only exert high forces in one direction due to the simultaneous expansion and contraction of piezo elements, making them unsuitable for applications requiring equal forces in both directions.
Innovation Solution
A piezo actuator design that includes at least one adjustment element to set a zero position, allowing for precise control of forward and backward movements by prestressing the piezo element arrangement, enabling forces to be exerted equally in both directions through the use of working elements and adjustment elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If piezo elements are arranged in series with the same polarization and controlled by a parallel circuit, then large movement amplitudes can be achieved with relatively small voltages, but the actuator can only exert high force in one direction (pressure mode)
Solution Approach 1:
The piezo element arrangement is divided into working elements and at least one adjustment element, allowing independent control of different functional groups. This segmentation enables the working elements to be optimized for bidirectional force while adjustment elements handle positioning, resolving the contradiction between movement amplitude and bidirectional force capability.
Solution Approach 2:
The adjustment element is used in a preliminary phase to set the zero position and prestress the piezo element arrangement before the working phase. This preliminary action compensates for play and establishes optimal initial conditions, enabling the working elements to exert high forces in both directions during subsequent operation.
2Measurement precision
If piezo elements are prestressed to compensate for play, then a defined zero position can be set, but the device complexity increases due to additional control phases
Solution Approach 1:
The adjustment element performs the zero position setting in a preliminary phase before the working phase. By separating the positioning function from the actuation function and executing it beforehand, the system achieves precise zero position setting without complicating the main working phase control.
Solution Approach 2:
The adjustment element serves multiple functions: it sets the zero position, compensates for play, and can contribute to forward and backward movements during the working phase. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise adjustment of the zero position and high force transmission in both directions, allowing for continuous and even movement by varying the voltages applied to the piezo elements, thus overcoming the limitations of existing piezo actuators.
Implementation Method 1
Piezo elements have the property that as soon as a positive electrical voltage is applied, they expand in a longitudinal direction, with a contraction always taking place orthogonally to the longitudinal direction.
Data Source
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AI summary
The invention relates to a piezo actuator (1) with multiple piezo elements (2a-2d) which carry out a mechanical movement in the longitudinal direction (L) by applying an electric voltage and thus cause a forwards and rearwards movement of the piezo actuator (1). According to the invention, the piezo actuator (1) comprises a controller (10, 11) which actuates at least one first piezo element (2a-2d) such that the first piezo element is elongated mechanically in a longitudinal direction (L) and a second piezo element (2a-2d) such that the second piezo element mechanically contracts in the longitudinal direction (L) in order to carry out both a forwards movement as well as a rearwards movement of the piezo actuator (1).