Excavator Swing Control with Regenerative Energy Absorption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The occurrence of an overrun phenomenon in excavators, where the rotational speed of the engine becomes excessively high due to regenerative energy generated during the deceleration of the swing hydraulic pump, is not effectively suppressed by existing technologies.
Innovation Solution
Incorporating a power take-off system with a swing hydraulic pump and motor, a neutral retention valve, and a regenerative energy absorbing device, which controls the meter-out opening based on the state of the regenerative energy absorbing device to manage and absorb regenerative energy, thereby preventing excessive engine speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If hydraulic oil is supplied from the swing hydraulic motor to the swing hydraulic pump via the neutral retention valve during deceleration, then regenerative energy is generated, but the rotational speed of the engine becomes excessively high causing overrun phenomenon
Solution Approach 1:
A regenerative energy absorbing device is introduced as an intermediary component between the swing hydraulic pump and the engine. This device absorbs the regenerative energy generated during swing deceleration, preventing it from being transmitted to the engine and causing overrun. The absorbing device acts as a mediator that decouples the energy recovery process from the engine speed control, allowing regenerative energy to be captured without affecting engine rotational speed stability.
Solution Approach 2:
The system dynamically adjusts the meter-out opening area of the neutral retention valve based on the state of the regenerative energy absorbing device. By changing the valve opening parameter, the system controls the flow rate of hydraulic oil to the absorbing device, thereby regulating the amount of regenerative energy absorbed. This parameter adjustment ensures that regenerative energy is effectively captured while preventing excessive engine speed increase.
2Use of energy by moving object
If the meter-out opening area of the neutral retention valve is increased to allow more hydraulic oil flow, then regenerative energy absorption is improved, but the control complexity increases
Solution Approach 1:
The valve control section implements a feedback control mechanism that continuously monitors the state of the regenerative energy absorbing device and adjusts the meter-out opening area of the neutral retention valve accordingly. The control section determines the required opening area based on the absorbing device's current state, creating a closed-loop control system. This feedback approach simplifies the control logic by using clear state-based decision rules rather than complex continuous control algorithms.
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
The solution effectively suppresses the overrun phenomenon by converting regenerative energy into thermal energy within the neutral retention valve, preventing excessive engine rotational speed and ensuring stable operation.
Implementation Method 1
a regenerative energy absorbing device that is coupled to the power take-off and absorbs regenerative energy generated by hydraulic oil supplied from the swing hydraulic motor to the swing hydraulic pump
Implementation Method 2
a neutral retention valve that is disposed in the first main oil passage and the second main oil passage and controls passage of hydraulic oil
Data Source
AI summary
An excavator includes: a swing motor driven by oil from a swing pump coupled to a power take-off and driven by an engine; a first main oil passage connecting a first discharge port of the swing pump and a first suction port of the swing motor; a second main oil passage connecting a second discharge port of the swing pump and a second suction port of the swing motor; a neutral retention valve disposed in the first main oil passage and the second main oil passage and controlling passage of oil; a regenerative energy absorbing device coupled to the power take-off and absorbs regenerative energy generated by oil from the swing motor to the swing pump via a meter-out opening of the neutral retention valve; and a valve control section controlling an area of the meter-out opening based on a state of the regenerative energy absorbing device.