Hydraulic Hybrid Flow Support Using an Accumulator for Peak Loads
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Construction machines, such as excavators, face inefficiencies in fuel consumption due to high engine speeds required for peak loads, leading to increased noise and parasitic losses in auxiliary drives.
Innovation Solution
A hydraulic hybrid system incorporating a main hydraulic machine, a support hydraulic machine, a hydraulic accumulator, and a control methodology that allows the system to operate in flow support, power boost, and charging modes, enabling reduced engine speed by utilizing the accumulator to provide power to working hydraulics, thereby reducing engine speed and parasitic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a relatively high engine speed is chosen to cover peak hydraulic flow requirements, then the hydraulic flow capacity is sufficient, but the average engine speed increases leading to reduced fuel efficiency
Solution Approach 1:
The system pre-charges the hydraulic accumulator during periods of low hydraulic demand when the engine operates at lower speeds. This preliminary energy storage enables the system to meet peak flow demands without requiring the engine to continuously operate at high speeds, thus improving fuel efficiency while maintaining hydraulic flow capacity.
Solution Approach 2:
The hydraulic accumulator acts as an intermediary energy storage device between the engine and the hydraulic system. It decouples the engine operation from immediate hydraulic flow demands, allowing the engine to operate more efficiently while the accumulator provides or absorbs hydraulic flow as needed to meet peak demands.
2Use of energy by moving object
If the engine speed is reduced to improve fuel efficiency, then fuel consumption decreases, but the maximum hydraulic flow capacity becomes insufficient for peak loads
Solution Approach 1:
The system pre-charges the hydraulic accumulator during low-demand periods, preparing energy reserves in advance. This allows the engine to operate at lower, more efficient speeds while the pre-charged accumulator can quickly discharge to meet sudden peak hydraulic flow requirements.
Solution Approach 2:
The system changes the operational parameters by introducing an energy storage medium (accumulator) that can rapidly change its energy state. The accumulator charge level dynamically adjusts to balance engine efficiency and hydraulic flow availability, enabling the engine to operate at optimal fuel efficiency points while maintaining peak flow capability through accumulator discharge.
3Productivity
If a single large hydraulic machine is used to meet peak flow demands, then the hydraulic capacity is sufficient, but the device complexity and cost increase
Solution Approach 1:
The hydraulic system is segmented into two distinct components: a main hydraulic machine for continuous operation and a support hydraulic machine coupled with an accumulator for peak demand supplementation. This segmentation allows each component to be optimized for its specific function, avoiding the need for a single oversized machine while reducing overall system complexity and cost.
Solution Approach 2:
The support hydraulic machine and accumulator combination serves multiple functions: it supplements hydraulic flow during peak demands, stores energy during low-demand periods, and enables the main hydraulic machine to operate at optimal efficiency points. This multi-functionality replaces what would otherwise require a single large, complex hydraulic machine.
4Productivity
If the main hydraulic machine capacity is increased to meet peak demands, then the hydraulic flow availability improves, but the parasitic losses in auxiliary drives increase
Solution Approach 1:
The accumulator is pre-charged during low-demand periods when auxiliary drives operate more efficiently. This preliminary energy storage allows the system to meet peak hydraulic demands without requiring the main hydraulic machine to be continuously oversized, thereby reducing parasitic losses in auxiliary drives while maintaining hydraulic flow availability.
Solution Approach 2:
The accumulator serves as an intermediary that decouples the hydraulic flow demand from the main hydraulic machine operation. By absorbing or supplementing flow demands, it allows the main hydraulic machine and auxiliary drives to operate at more efficient points, reducing parasitic losses while maintaining overall hydraulic flow 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 enhances fuel efficiency, reduces noise, and extends the maximum available hydraulic flow beyond the capacity of the main hydraulic machine, optimizing engine operation and minimizing auxiliary drive losses.
Implementation Method 1
a hydraulic accumulator
Implementation Method 2
The hydraulic system based on hydraulic accumulators
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a hydraulic system (100) for a work machine. The system comprising: a main hydraulic machine (102) connected to an output shaft (104) of an engine (106) of the work machine for providing power to working hydraulics (110) of the work machine; a main pressure line (108) connecting the main hydraulic machine to the working hydraulics; a support hydraulic machine (112) connected to the output shaft; a hydraulic accumulator (114); a discharge valve (116) connected between the accumulator and an input side (118) of the support hydraulic machine; a charge valve (120) connected between an output side (122) of the support hydraulic machine and the hydraulic accumulator to selectively allow a flow from the support hydraulic machine to the hydraulic accumulator; a flow support valve (124) connected between the output side of the support hydraulic machine and the main pressure line to selectively allow a flow from the support hydraulic machine to the main pressure line; and a hydraulic tank (126) connected to the input side of the support hydraulic machine.