Patent ID: 8437926
Filing Date: 2013-05-07
Classification: E02F

Abstract:
1. A control device for automatically controlling a pitch angle of a blade relative to the ground, the control device being provided to construction machine including the blade, a blade tilt cylinder and a blade tilt cylinder valve constituting a part of a main valve, the blade tilt cylinder valve being linked to the blade tilt cylinder, the control device comprising: a hydraulic oil amount calculation unit configured to calculate an amount of hydraulic oil passing through the blade tilt cylinder valve based on an open ratio and a cumulative time of opening of the blade tilt cylinder valve; and an open ratio setting unit configured to cause the blade tilt cylinder valve to open at a predetermined open ratio when a request for the pitch angle to be changed from a first angle to a second angle has been received, the open ratio setting unit being configured to cause the blade tilt cylinder valve to close when the calculated amount of hydraulic oil has reached a predetermined amount of hydraulic oil required for the change from the first angle to the second angle, the open ratio setting unit being configured to cause the open ratio to be smaller than the predetermined open ratio while a request for a predetermined action necessitating that hydraulic oil be supplied from the main valve is being received.