| 摘要 |
A length sensor for measuring a length-change of a component (1), such as a closed tubular body, more specifically a shaft etc, containing a high-pressure fluid, has at least one piezoelectric element (2) clamped between two retaining parts (3,4) rigidly joined to the component (1) so that a length-change (delta1) of the component (1) effects a change in mechanical stress/tension and thereby a change in an electrical property of the piezoelectric element (2), the latter being specifically a ring-shaped body surrounding the component (1). An electronic evaluating circuit (10) generates a measurement signal in relation to the change of the electrical property of the piezoelectric element (2). The piezoelectric element (2) is clamped by the two retaining parts (3,4) so that a change in length (delta1) of the component (1) specifically effects a change in the compressive stress or in the tensile stress of the piezo-electric element (2).
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