Hydraulic Pump Displacement Control for Hybrid Construction Machine Fuel Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hybrid construction machines that adjust engine rotation speed to reduce fuel consumption cause a change in hydraulic pump discharge flow rate, leading to an unusual operating feel for operators compared to traditional machines.
Innovation Solution
A hybrid construction machine with a variable displacement hydraulic pump, an engine, an electric motor, and a controller that calculates and controls engine and hydraulic pump parameters to maintain a constant discharge flow rate, ensuring the engine rotation speed aligns with target values to minimize fuel consumption while maintaining similar operation to traditional machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the rotation speed of the engine is changed in accordance with the power absorbed by the hydraulic pump to reduce fuel consumption, then fuel consumption is reduced, but the discharge flow rate of the hydraulic pump changes causing unusual operation feeling
Solution Approach 1:
The patent applies dynamics by making the hydraulic pump displacement variable rather than fixed. The controller dynamically adjusts the pump displacement based on engine rotation speed changes, ensuring that the discharge flow rate remains constant even as engine speed varies for fuel efficiency. This dynamic adjustment resolves the contradiction by allowing engine speed optimization while maintaining consistent hydraulic output for normal operation feeling.
Solution Approach 2:
The patent changes the parameter of pump displacement to compensate for engine rotation speed variations. By calculating the required displacement based on target flow rate and actual engine speed, the system maintains constant hydraulic output despite engine speed changes aimed at reducing fuel consumption. This parameter change strategy allows simultaneous achievement of fuel efficiency and operational consistency.
2Loss of energy
If the engine rotation speed is adjusted to operate in high-efficiency range, then energy efficiency is improved, but the hydraulic pump discharge flow rate becomes inconsistent with operator expectations
Solution Approach 1:
The patent implements feedback control where the controller continuously monitors engine rotation speed and hydraulic pump discharge flow rate. Based on this feedback, the system adjusts the pump displacement to maintain the target flow rate while allowing the engine to operate at optimized speeds for energy efficiency. This closed-loop feedback mechanism resolves the contradiction between energy efficiency and flow rate consistency.
Solution Approach 2:
The system dynamically adjusts pump displacement in response to engine speed changes. When the engine operates at reduced speeds for efficiency, the pump displacement is increased proportionally to maintain the required discharge flow rate. This dynamic compensation ensures energy efficiency is improved without compromising the consistency of hydraulic output that operators expect.
Data Source
AI summary
A hybrid construction machine is provided with a variable displacement hydraulic pump 1 which supplies hydraulic oil to a hydraulic actuator, an engine 2 which is provided to be able to drive and rotate the hydraulic pump 1, an electric motor 3 which is provided to be able to drive and rotate the hydraulic pump 1, an engine control dial 4, a controller 4 and an operating lever 5. The controller changes the rotation speed of the engine 2 to reduce fuel consumption according to power generated by the engine 2, and changes displacement of the hydraulic pump 1 based on the rotation speed of the engine 2, the dial position of the engine control dial 4 and the amount of operation on the operating lever 5.