Hydraulic Excavator Drive Control System Torque Distribution
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Solution Overview
Problem
The existing drive control systems for operating machines, such as hydraulic excavators, face inefficiencies when using electric motors and oil-pressure motors together, as they consume excessive energy and lead to short drive times due to low electric power efficiency and rapid depletion of stored electric power.
Innovation Solution
A drive control system that includes a power storage device, an electric motor, a liquid-pressure motor, and a control device that adjusts the torque of both motors to maximize electric power efficiency by using high-efficiency torque curves and regenerative capabilities, allowing the electric motor to operate efficiently and extending its drive time while reducing the energy needed for the oil-pressure motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the electric motor drives at maximum torque to provide sufficient turning force, then the required torque is achieved, but the electric power efficiency becomes low and the stored electric power depletes rapidly
Solution Approach 1:
The control device dynamically adjusts the electric motor's torque output parameter based on the structure's rotating speed and remaining electric power levels. By changing the torque parameter from maximum to optimized values, the system achieves sufficient turning force while maintaining higher electric power efficiency and extending drive time
Solution Approach 2:
The system transitions from a static maximum torque mode to a dynamic torque control mode where the electric motor's output is continuously adjusted according to real-time conditions (rotating speed, power availability). This dynamic adjustment allows the system to optimize the balance between torque delivery and energy consumption throughout the driving cycle
2Power
If the electric motor keeps driving at maximum torque, then the required power output is maintained, but the drive time becomes short due to rapid depletion of stored electric power
Solution Approach 1:
The control device performs preliminary assessment of the structure's inertial characteristics and remaining electric power before initiating maximum torque output. By predicting the power consumption trajectory in advance, the system determines the optimal duration and intensity of high-torque phases, thereby extending overall drive time while maintaining necessary power output when required
3Force
If the oil-pressure motor provides residual torque to supplement the electric motor, then the total torque requirement is met, but the energy efficiency advantage is reduced when the electric motor operates at low efficiency
Solution Approach 1:
The control device continuously monitors the electric motor's operating efficiency and the structure's rotating speed, using this feedback to dynamically determine the optimal torque distribution between the electric motor and oil-pressure motor. When electric power efficiency is high, the system maximizes electric motor contribution; when efficiency drops, it strategically transitions to oil-pressure motor supplementation, thereby minimizing overall energy loss
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the electric motor's efficiency, prolongs its drive time, and reduces the energy consumption of the oil-pressure motor, thereby improving overall energy usage and extending the operating time of the machine.
Implementation Method 1
an electric motor supplied with electric power from a power storage device to operate and turn a structure of the operating machine
Implementation Method 2
a liquid-pressure motor supplied with operating liquid to operate and turn the structure in cooperation with the electric motor
Data Source
AI summary
A drive control system of a hydraulic excavator includes a control device. When accelerating a turning body to a target turning speed, the drive control device controls an operation of the electric motor driving device such that the electric motor outputs high efficiency torque by which a highest electric power efficiency is obtained at the target turning speed. The control device controls an operation of an oil pressure supply device such that residual torque obtained by subtracting the high efficiency torque from target torque is output from an oil-pressure motor.