Chad Alan Patterson

US Patent:

7624671, Dec 1, 2009

Filed:

Feb 7, 2007

Appl. No.:

11/703314

Inventors:

Brian Nielsen - Viborg, DK
Ole Ploug - Roedekro, DK
Chad M. Patterson - Huxley IA, US

Assignee:

Sauer-Danfoss Aps - Nordborg

International Classification:

F15B 11/00
F16H 61/42

US Classification:

91 31, 91459, 60422

Abstract:

A hydraulic actuator for a hydraulic servomotor () is disclosed. The hydraulic servomotor () is of a kind having at least one defined end position, and has a first chamber () and a second chamber () associated therewith. The actuator is connected to a fluid source () and a fluid drain (). The actuator comprises a first valve () fluidly connected between the fluid source () and the first chamber (), a second valve () fluidly connected between the first chamber () and the fluid drain (), and a third valve () fluidly connected between the fluid source () and the second chamber (). The actuator further comprises a flow channel (), preferably comprising a flow restrictor (), in fluid communication with the second chamber (). The valves () are such that, in the case of a power cut off, they will prevent a fluid flow out of the first chamber (), and a fluid flow out of the second chamber () takes place via the flow channel (). This will cause a servomotor piston member () to move towards the second chamber (), thereby moving the hydraulic servomotor () to an end position.