Fault Isolation and Recovery Procedures for Electrohydraulic Valves

Abstract

A method for isolating faulty or blocked work ports in an electrohydraulic system is disclosed. In one step, the system pump is set to a first predetermined pressure and the valve assembly is commanded to a center position. In another step, the central position of the valve is recorded. In one step, the valve assembly is opened to place a work port associated with the valve in fluid communication with the pump, after which a first end position of the valve, a first work port pressure and a first pump supply are recorded pressure. In another step, the valve assembly is opened to place the working port into a reservoir, after which the second end position of the valve and the fluid pressure associated with the working port are recorded. The recorded and measured data can then be analyzed to identify fault conditions or blocked working ports.

Description

[0001] related application

[0002] This application was filed as a PCT International Patent Application on December 23, 2013, and claims priority to U.S. Patent Application Serial No. 61 / 745,947, filed December 26, 2012, the disclosure of which is hereby incorporated in its entirety Incorporated by reference. Background technique

[0003] Work machines such as forklifts, wheel loaders, track loaders, excavators, trenchers, bulldozers and telehandlers are well known. Work machines may be used to move materials such as pallets, dirt and / or debris. Work machines typically include a work implement (eg, a fork) connected to the work machine. Work implements attached to work machines are typically powered by hydraulic systems. A hydraulic system may include a hydraulic pump powered by a prime mover such as a diesel engine. Work machines often have electronic control systems that rely on multiple inputs and outputs, such as pressure sensors, position sensors, and valve actuators...

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