Patent ID: 9284719
Filing Date: 2016-03-15
CPC Classification: E02F,F15B

Claim Text:
1. A hydraulic system for a construction machine, comprising: a plurality of electronic hydraulic pumps, which are pressure control type variable capacity pumps; a plurality of main control valves configured to selectively control a movement of working oil discharged from the plurality of electronic hydraulic pumps; a plurality of working machines and travel motors, each of the plurality of working machines and travel motors driven with working oil supplied from a respective one main control valve of the plurality of main control valves; and an electronic control unit configured to control a discharge flow rate of the working oil discharged from the plurality of electronic hydraulic pumps based on flow rate signals of the plurality of electronic hydraulic pumps and an output signal from a joystick, wherein when the electronic control unit is not able to perform a normal control due to a failure of transmittance of the output signal from the joystick to the electronic control unit, the electronic control unit is configured to perform an emergency control of permitting the plurality of electronic hydraulic pumps to discharge the working oil with a maximum pressure by outputting predetermined pressure control signals to the plurality of electronic hydraulic pumps, and the electronic control unit is configured to perform a predetermined control of a swash plate angle that permits the plurality of electronic hydraulic pumps to discharge the working oil at a predetermined flow rate and at a minimum pressure when the joystick is in a neutral state during the emergency control.