Excavator Swing Pump Flow Control for Inertia-Responsive Operation
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Solution Overview
Problem
Existing work machines, such as hydraulic excavators, face inefficiencies in swing operation due to constant rate of increase in delivery flow rate based solely on moment of inertia, leading to unintended large swing angular acceleration during minimal operator input when moment of inertia is small.
Innovation Solution
A work machine system that includes sensors to detect operation amount and state quantities, calculates a target maximum flow rate and rate of increase for the hydraulic pump, allowing the rate of increase in delivery flow rate to vary according to both moment of inertia and operation amount, thereby controlling the flow rate more precisely.
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 causing large swing angular acceleration when moment of inertia is small
Solution Approach 1:
The patent changes the control parameters from solely moment of inertia to a combination of moment of inertia and operation amount. The controller calculates a rate of increase in delivery flow rate that considers both parameters, allowing adaptive adjustment of pump flow rate that prevents excessive swing acceleration while maintaining energy efficiency.
Solution Approach 2:
The patent implements dynamic control by continuously monitoring operation amount and moment of inertia, then adjusting the rate of increase in delivery flow rate in real-time. This dynamic approach allows the system to respond appropriately to varying operational conditions, preventing both energy waste and unintended motion.
2Speed
If the delivery flow rate is increased rapidly to respond to operator input, then operability is improved for quick swing response, but energy efficiency deteriorates due to excessive relief valve discharge
Solution Approach 1:
The patent calculates the appropriate rate of increase in delivery flow rate in advance based on moment of inertia and operation amount, then applies this pre-calculated rate to control the pump. This preliminary calculation prevents excessive flow rate increase that would cause relief valve discharge, while still providing adequate swing response.
Solution Approach 2:
The patent uses feedback from operation amount sensors and moment of inertia calculations to continuously adjust the rate of increase in delivery flow rate. This feedback mechanism ensures the pump delivers the precise flow rate needed for the current operational conditions, preventing both energy waste and inadequate response.
Data Source
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).