Patent ID: 8930094
Filing Date: 2015-01-06
Classification: B66C

Abstract:
1. A control device for a hydraulic winch, comprising: a hydraulic source; a variable-displacement hydraulic motor that is caused to rotate by pressure oil from the hydraulic source and is used to drive a winch drum; a winch operation member that outputs a low-speed hoisting/lowering command so as to hoist/lower a hook at low speed when operated to a low-speed side hoisting/lowering operating position and outputs a high-speed hoisting/lowering command so as to hoist/lower the hook at high speed when operated to a high-speed side hoisting/lowering operating position; an accelerator operation quantity detection unit that detects an operation quantity of an accelerator operation member; an engine control unit that controls an engine rotation speed at an engine within a range between a minimum rotation speed and a maximum rotation speed, in correspondence to the operation quantity at the accelerator operation member detected by the accelerator operation quantity detection unit; a rotation speed detection unit that detects the engine rotation speed; a line pull detection unit that detects a line pull at a hoisting rope; a condition decision unit that decides that a fuel-efficient, high-speed operation condition is established in response to an operation performed at the winch operation member to switch from the low-speed side hoisting/lowering operating position to the high-speed side hoisting/lowering operating position when the engine rotation speed detected by the rotation speed detection unit is equal to or lower than a predetermined rotation speed and the line pull detected by the line pull detection unit is equal to or less than a predetermined value; and a motor displacement control unit that reduces a motor displacement of the hydraulic motor and controls the motor displacement at a minimum displacement once the condition decision unit decides that the fuel-efficient, high-speed operation condition has been established, wherein: once the condition decision unit decides that the fuel-efficient, high-speed operation condition has been established, the engine control unit sets an upper limit to the engine rotation speed at a predetermined rotation speed, lower than the maximum rotation speed.