Working Machine Hydraulics with Make-Up Flow and Energy Recuperation
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Solution Overview
Problem
Existing hybrid hydraulic systems in working machines, such as wheel loaders, face inefficiencies due to the direct coupling of driveline and work hydraulics systems, leading to problematic interactions and reduced fuel efficiency, especially when handling heavy loads in construction environments.
Innovation Solution
A dual electric and hydraulic machine system is introduced, where the second hydraulic machine provides additional flow or recovers energy when the first hydraulic machine's flow is exceeded, offering redundancy and flexibility by allowing the system to operate even if one machine malfunctions, and enabling energy storage through an accumulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a hybrid hydraulic system is used to improve fuel efficiency, then energy recuperation is enabled, but system complexity increases due to additional electric machines and energy storage components
Solution Approach 1:
The first electric machine is designed to perform multiple functions: it operates as a motor during acceleration phases and as a generator during deceleration phases. This multi-functionality reduces the need for separate dedicated components for each function, thereby improving fuel efficiency while limiting the increase in system complexity.
Solution Approach 2:
The system implements energy recuperation by capturing kinetic energy during deceleration through the first electric machine operating as a generator, storing this energy in the energy storage device, and reusing it during acceleration. This recovery mechanism improves overall energy efficiency by converting previously wasted energy into useful work.
2Device complexity
If the driveline and work hydraulics systems are directly coupled to the engine shaft, then power transmission is simplified, but problematic interactions occur reducing overall efficiency
Solution Approach 1:
The first hydraulic machine acts as an intermediary between the driveline and work hydraulics systems. It decouples the direct coupling, allowing independent control of each system while maintaining power transmission. This intermediary component enables efficient energy management by facilitating energy exchange between the driveline and hydraulic systems without problematic interactions.
Solution Approach 2:
The patent replaces direct mechanical coupling with a hydraulic-mechanical system involving the first hydraulic machine. This substitution allows for more flexible and efficient energy management by enabling energy recuperation and transfer between the driveline and work hydraulics, improving operational efficiency while maintaining manageable system complexity.
3Device complexity
If a single hydraulic machine is used, then system design is simpler, but redundancy is lost reducing reliability
Solution Approach 1:
The hydraulic system is segmented into two independent hydraulic machines (first and second hydraulic machines), each capable of performing the same function. This segmentation provides redundancy, ensuring that if one machine fails, the other can maintain system operation, thereby improving reliability while keeping the design relatively simple through modular architecture.
Solution Approach 2:
The system incorporates redundant hydraulic machines as a preventive measure against failures. By having backup capacity built into the system design, the patent ensures continuous operation even when one machine malfunctions, providing beforehand cushioning against potential reliability issues.
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 configuration enhances energy efficiency, flexibility, and system reliability by allowing energy recuperation and additional hydraulic flow when needed, reducing losses and enabling safe operation even with reduced capacity.
Implementation Method 1
the second hydraulic machine is configured to provide a flow of hydraulic fluid from a hydraulic fluid supply to the input side of the first hydraulic machine
Implementation Method 2
to recuperate energy if the requested flow from the first hydraulic machine is lower than the flow of the first return line
Data Source
AI summary
A hydraulic system includes a first electric machine connected to a first hydraulic machine and a second electric machine connected to a second hydraulic machine. An output side of the second hydraulic machine is connected to an input side of the first hydraulic machine. A hydraulic consumer is hydraulically coupled to an output side of the first hydraulic machine via a supply line and is powered by the first hydraulic machine. A return line hydraulically couples the hydraulic consumer to an input side of the first hydraulic machine. The second hydraulic machine provides a flow of hydraulic fluid to the input side of the first hydraulic machine if a requested flow from the first hydraulic machine exceeds a flow of the return line and recuperates energy if the requested flow from the first hydraulic machine is lower than the flow of the return line.