Hydraulic device and a pivot joint

Abstract

A hydraulic device () comprises a housing () and a shaft () which is rotatable about a first axis of rotation (). The shaft () has a flange (), a partly spherical portion () and a plurality of pistons (), which are fixed to the flange (). The device () also has a plurality of cylindrical sleeves (), wherein each sleeve () has a sleeve bottom () comprising a sleeve opening () including a centreline (). The sleeves () cooperate with the pistons () to form respective compression chambers () of variable volume. A barrel plate () is mounted on the partly spherical portion () and has barrel plate ports () including respective centrelines (). The sleeves () are rotatable about a second axis of rotation () which intersects the first axis of rotation () by an acute swash angle. The barrel plate () is coupled to the shaft () in rotational direction thereof by means of a plurality of pin-groove couplings creating a plurality of pivot axes () about the second axis of rotation (). The widths of the grooves () allow the pins () to move within the respective corresponding grooves () in rotational direction about the second axis of rotation () under operating conditions. The relative position of the shaft () and the barrel plate () in rotational direction about the second axis of rotation () is adapted such that under operating conditions each centreline () of the respective barrel plate ports () fluctuates in rotational direction about the second axis of rotation () with respect to the centreline () of the corresponding sleeve opening () within a range in which the centreline () of the sleeve opening () lies.