Hydraulic drive system

摘要

A hydraulic drive system includes a pump, a steering actuator, a loading/unloading apparatus actuator, a drive device, a relief valve, and an input unit. The drive device: flows hydraulic oil from the pump to the loading/unloading apparatus actuator when an operating tool is operated; flows the hydraulic oil from the pump to the steering actuator when a steering has become an operated state from a non-operated state regardless of an operation of the operating tool; and causes the hydraulic oil from the pump to be discharged to a tank via the relief valve to increase the torque of an engine when an increase instruction is inputted to the input unit and the steering is in a non-operated state.

主权项

1. A hydraulic drive system to be applied to construction machinery, the construction machinery including: a steering for steering a wheel; a loading/unloading apparatus; and an operating tool for operating the loading/unloading apparatus,
the hydraulic drive system comprising: a pump configured to be driven by an engine and discharge hydraulic oil; a steering actuator connected to the pump and configured to operate based on the hydraulic oil from the pump; a loading/unloading apparatus actuator connected to the pump in parallel with the steering actuator and configured to operate based on the hydraulic oil from the pump; a drive device configured to control a flow of the hydraulic oil from the pump in accordance with an operation of the operating tool and an operation of the steering; a relief valve configured to discharge the hydraulic oil from the pump to a tank when a discharge pressure of the pump has become a predetermined pressure or higher; and an input unit for inputting an increase instruction to increase a torque of the engine, wherein the drive device:
flows the hydraulic oil from the pump to the loading/unloading apparatus actuator when the operating tool is operated;flows the hydraulic oil from the pump to the steering actuator when the steering has become an operated state from a non-operated state regardless of an operation of the operating tool;causes the hydraulic oil flowing from the pump to the steering actuator to be discharged to the tank via the relief valve to increase the torque of the engine when the increase instruction is inputted to the input unit and the steering is in a non-operated state; andflows the hydraulic oil from the pump to the steering actuator when the increase instruction to increase the torque of the engine is inputted to the input unit and the steering is operated.