System for determining the position of a piston along its path of travel for a fluid-dynamic actuator

摘要

A fluid-dynamic actuator having a detection system for determining the position of a piston along its path of travel within a cylinder. The piston includes a head and rod extending therefrom. First grooves are machined on respective sections of the rod. Projections of the first grooves onto a first plane parallel to the longitudinal axis of the rod define segments arranged obliquely with respect to the axis. Second grooves extend along the axis for predetermined lengths such that a respective number of second grooves run across each section. Optical sensors detect the presence of second grooves through a second plane transverse to the axis and a displacement of segments along a line coplanar with the second plane due to movement of the piston. A processor counts detected second grooves to determine the position of the piston as a function of the count of second grooves and the displacement of segments.

主权项

1. A fluid-dynamic actuator comprising: a cylinder (2) and a piston (3), which includes a rod (5) having a longitudinal axis (6); the piston (3) being movable inside the cylinder (2) along a path of travel (9) parallel to said axis (6); the actuator (1) further including a detection system (13) for determining a position of the piston (3) along a path of travel (9), and wherein said detection system (13) comprises: a plurality of first grooves (14), which are machined on an outer surface of respective sections (15) of the rod (5) so that respective projections of the first grooves (14) onto a first plane parallel to the axis (6) define respective first segments (14a) parallel to one another and arranged obliquely with respect to a projection of the axis (6) onto the first plane; a plurality of second grooves (17), which are machined on an outer surface of the rod (5) and extend parallel to the axis (6) for respective lengths such that a respective number of second grooves (17) run across the outer surface of each of the sections (15); optical sensing means (19, 21) to detect the presence of second grooves (17) in correspondence with a second plane (20) transversal to the axis (6) and fixed with respect to the cylinder (2) and a first displacement (32) of the first segments (14a) along a reading line (31) defined by an intersection of the second plane (20) with the first plane, said first displacement (32) being due to a movement of the piston (3) along the path of travel (9); and processing means (22) to identify the section (15) of rod (5) present in correspondence with the second plane (20) by counting the detected second grooves (17) and to measure the position of the piston (3) along the path of travel (9) as a function of the identified section (15) and of said first displacement (32).