Excavator Swing Pump Flow Control for Inertia-Adaptive Response
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Solution Overview
Problem
Existing work machines, such as hydraulic excavators, face inefficiencies in pump flow control during swing operations due to constant rate of increase in delivery flow rate based on moment of inertia, leading to excessive swing angular acceleration and energy wastage, especially when the moment of inertia is small.
Innovation Solution
A work machine with a variable displacement hydraulic pump, regulated by a system that adjusts the delivery flow rate based on both the moment of inertia and the operation amount, using sensors to detect operation and state quantities, and a controller that calculates a target maximum flow rate and rate of increase to optimize energy efficiency and operability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the rate of increase in delivery flow rate is limited only according to moment of inertia, then energy efficiency is improved by reducing relief valve discharge, but operability deteriorates with excessive swing angular acceleration when moment of inertia is small
Solution Approach 1:
The patent applies dynamics by making the flow rate control adaptive rather than static. The controller dynamically adjusts the rate of increase in delivery flow rate based on real-time detection of operation amount and moment of inertia, allowing the system to respond flexibly to varying operational conditions. This resolves the contradiction by enabling the system to maintain energy efficiency when needed while preventing excessive acceleration when the operator requires controlled movement.
Solution Approach 2:
The patent changes the control parameter from a fixed rate of increase based solely on moment of inertia to a variable rate that considers both moment of inertia and operation amount. The controller calculates an appropriate rate of increase by combining these two parameters, allowing the delivery flow rate to increase at different rates depending on the specific operational context, thus resolving the contradiction between energy efficiency and operability.
2Speed
If delivery flow rate increases rapidly to respond to swing operation, then operability is improved, but energy efficiency deteriorates due to excessive pressure and relief valve discharge
Solution Approach 1:
The system dynamically controls the delivery flow rate increase rate rather than using a fixed rapid increase. The controller continuously monitors operation amount and moment of inertia to determine the appropriate rate of flow rate increase, enabling the system to respond quickly when necessary while avoiding excessive pressure buildup that would cause energy wastage through the relief valve.
Solution Approach 2:
The patent implements feedback control by detecting operation amount and moment of inertia, then using this information to adjust the delivery flow rate increase rate. The controller receives feedback about the current operational state and adjusts the pump's delivery flow rate accordingly, preventing both overly rapid increases that waste energy and overly slow increases that reduce responsiveness.
Data Source
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AI summary
To control a rate of increase of a delivery flow rate of a pump for a swing operation in response to a moment of inertia and an operation amount and to achieve both energy efficiency and operability with respect to the swing operation, a work machine including a swing structure 2 disposed on an upper portion of a track structure 1, a work implement 3 disposed in the swing structure 2, a swing motor 16, a hydraulic pump 22, a regulator 24, a directional control valve 31, and an operation device 34 further includes: a target maximum flow rate calculation section 53 configured to calculate a target maximum flow rate Qmax of the pump to correspond to a swing operation amount Ps; a flow rate rate-of-increase calculation section 55 configured to calculate a rate of increase dQ of a command flow rate of the hydraulic pump 22 on a basis of the moments of inertia of the swing structure 2 and the work implement 3 and the swing operation amount Ps; a command flow rate calculation section 56 configured to calculate a command flow rate Q(t) on a basis of the rate of increase dQ with the target maximum flow rate Qmax set as an upper limit; and an output section 57 configured to output a command signal Sf to the regulator 24 corresponding to the command flow rate Q(t).