Swing Motor Pressure Switching for Excavator Speed Tracking
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Solution Overview
Problem
The existing swing motor systems in construction machines, such as hydraulic excavators, face inefficiencies in rotational acceleration due to random pressure variations, making it difficult to achieve the desired rotational acceleration intended by the operator.
Innovation Solution
A construction machine equipped with a rotational speed sensor, pressure sensor, and a controller that adjusts the swing motor's driving pressure and flow rate to match the target rotational speed and moment of inertia, allowing for precise control of the swing motor's rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the swing motor supply flow rate is controlled based on deviation between target and actual rotational speed, then the speed following characteristic is improved, but the swing motor torque cannot be adjusted and desired rotational acceleration cannot be obtained
Solution Approach 1:
The patent applies dynamics by making the control strategy adaptive based on the deviation magnitude. The controller dynamically switches between two control modes: when deviation exceeds a threshold, pressure control is applied for acceleration; when deviation is within threshold, flow rate control is applied for speed following. This dynamic adaptation resolves the contradiction by selecting the appropriate control parameter based on real-time conditions.
Solution Approach 2:
The patent changes the control parameter from fixed flow rate control to variable pressure control based on deviation magnitude. By changing the controlled parameter (pressure vs. flow rate) according to the deviation between target and actual rotational speed, the system can simultaneously achieve both torque control for acceleration and speed following, resolving the contradiction between these two requirements.
2Speed
If the driving pressure of the swing motor is controlled to coincide with target driving pressure, then the rotational acceleration is improved, but the rotational speed adjustment precision deteriorates
Solution Approach 1:
The patent implements periodic action by dividing the control process into two distinct phases: a pressure control phase for acceleration when deviation is large, and a flow rate control phase for precision speed adjustment when deviation is small. This periodic switching between control modes ensures both rapid acceleration and precise speed adjustment are achieved at different stages of the operation.
Solution Approach 2:
The patent applies preliminary action by first applying pressure control to rapidly reduce the deviation between target and actual rotational speed to within a predetermined threshold. Once this preliminary acceleration phase is complete and the deviation is small, the system switches to flow rate control for precise speed adjustment, ensuring both phases contribute to the overall control objective.
3Loss of energy
If the pump flow rate is controlled to reduce excess flow rate, then energy efficiency is improved, but the swing motor torque becomes random and cannot achieve desired rotational acceleration
Solution Approach 1:
The patent applies feedback by continuously monitoring the deviation between target and actual rotational speed, and using this feedback to determine the appropriate control mode. When deviation is large, pressure control with feedback ensures sufficient torque for acceleration; when deviation is small, flow rate control with feedback maintains energy efficiency while achieving precise speed following, thus resolving the contradiction between energy efficiency and torque availability.
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 enables the construction machine to promptly adjust the swing motor's rotational speed to the target speed, improving energy efficiency and ensuring the desired rotational acceleration is achieved.
Implementation Method 1
a rotational speed sensor that detects a rotational speed of the swing motor
Implementation Method 2
a pressure sensor that detects a driving pressure of the swing motor
Implementation Method 3
a hydraulic pump that delivers hydraulic operating fluid sucked from the hydraulic operating fluid tank
Implementation Method 4
a swing motor that is supplied with the hydraulic operating fluid from the hydraulic pump and drives the swing structure
Data Source
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AI summary
Provided is a construction machine which can promptly adjust the rotational speed of a swing motor to a target rotational speed. A controller calculates a target rotational speed of the swing motor based on input from an operation device, calculates a degree of deviation of a rotational speed detected by a rotational speed sensor from the target rotational speed, sets a target driving pressure of the swing motor according to a moment of inertia about a swing axis of a swing structure and a work device and controls a pressure adjusting device in such a manner as to reduce a difference between a driving pressure detected by a pressure sensor and the target driving pressure, when the degree of deviation is larger than a predetermined value, and controls the pressure adjusting device in such a manner as to reduce a difference between the rotational speed detected by the rotational speed sensor and the target rotational speed, when the degree of deviation is equal to or smaller than the predetermined value.