Position sensing hydraulic cylinder

摘要

A hydraulic cylinder has an internal shaft that rotates in response to extension or contraction of an output rod. A magnet is affixed to the shaft, the position of which is detected by a sensor internal to the hydraulic cylinder for determining the position of the output rod.

主权项

1. A hydraulic cylinder comprising:
a barrel with an end cap on a first end thereof defining a first working end of the hydraulic cylinder; a rod that extends from a second end of the barrel in response to hydraulic pressure applied to an attached piston within the barrel, the output rod defining a second working end of the hydraulic cylinder; a helical shaft having a magnet on a first end thereof and extending into the rod on a second end thereof; and a bushing in a fixed relationship with respect to the rod; a magnetic sensor for sensing the linear position of the piston, contained inside the end cap of the hydraulic cylinder and mechanically isolated from the rod and the hydraulic pressure applied to the piston; wherein the first end of the helical shaft is affixed to the end cap with the magnet within sensing proximity of the magnetic sensor, which senses the rotational position of the helical shaft relative to the end cap; and wherein the bushing mates with the helical shaft in a sliding relationship such that the helical shaft is rotated in response to extension or contraction of the rod from the barrel.