Hydraulic Accumulator Supply Control for Low-Loss Work Machine Drives
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Solution Overview
Problem
Existing hydraulic drive systems for work machines suffer from efficiency losses due to surplus pressure loss and energy loss when hydraulic fluid is temporarily accumulated in an accumulator, especially when increasing traveling speed, and mechanical inefficiencies arise from dedicated pump motors connected to engines, leading to ineffective utilization of accumulated fluid.
Innovation Solution
A hydraulic drive system with dual circuits supplying hydraulic fluid directly from the pump or from an accumulator to the hydraulic cylinder via flow control valves, allowing the system to choose the more efficient path based on operation demands, reducing energy loss and improving overall efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If hydraulic fluid is temporarily accumulated in the accumulator when increasing traveling speed, then the hydraulic cylinder can be operated, but surplus pressure loss and energy loss due to leakage occur, deteriorating efficiency
Solution Approach 1:
The system dynamically switches between two operational modes: accumulating hydraulic fluid in the accumulator during low-demand periods, and directly supplying hydraulic fluid from the pump to the hydraulic cylinder during high-speed travel operations. This dynamic adaptation eliminates energy loss while maintaining operational flexibility.
Solution Approach 2:
The control device changes the operational parameters of the hydraulic system by detecting travel speed and selectively activating either the accumulator supply path or the direct pump-to-cylinder path, thereby optimizing energy efficiency based on real-time operational conditions.
2Power
If hydraulic fluid is accumulated in the accumulator when engine load is low, then engine load can be leveled and engine size reduced, but mechanical efficiency and volume efficiency decrease due to drag loss from dedicated pump motor
Solution Approach 1:
The main hydraulic pump serves multiple functions: it can directly supply hydraulic fluid to actuators during high-speed operations and can simultaneously charge the accumulator during low-speed operations. This eliminates the need for a dedicated pump motor, removing the associated drag loss while maintaining engine load leveling capability.
Solution Approach 2:
The system merges the accumulation function and the direct supply function into a single hydraulic pump system, controlled by a control device that routes hydraulic fluid appropriately. This consolidation eliminates redundant components and their associated energy losses.
3Loss of energy
If hydraulic fluid is supplied directly from hydraulic pump to hydraulic cylinder, then efficiency is improved, but the accumulator cannot be charged to assist during high load conditions
Solution Approach 1:
The control device dynamically switches between direct supply mode (pump to cylinder) for efficiency during normal operations and accumulator supply mode for assistance during high-load conditions, thereby maintaining both energy efficiency and system reliability.
Solution Approach 2:
The accumulator is pre-charged with hydraulic fluid during low-demand periods through the controlled opening of the accumulation flow adjustment device, preparing energy reserves in advance for high-load conditions without affecting current operational efficiency.
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 significantly improves the efficiency of the work machine by minimizing energy loss and fuel consumption, allowing for optimal hydraulic fluid distribution and reducing engine load, thereby enhancing operational efficiency and reducing fuel usage.
Implementation Method 1
a hydraulic pump, and a hydraulic cylinder (actuator) operated by the hydraulic fluid from the hydraulic pump
Implementation Method 2
an accumulator accumulating a hydraulic fluid delivered from the hydraulic pump
Data Source
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AI summary
It is an object of the present invention to provide a hydraulic drive system that effectively utilizes a hydraulic fluid accumulated in an accumulator to make it possible to achieve a substantial improvement in terms of efficiency for a work machine as a whole. A hydraulic drive system includes: a first hydraulic pump; a first hydraulic actuator driven by being supplied with a hydraulic fluid from the first hydraulic pump; a first line for supplying the hydraulic fluid from the first hydraulic pump to the first hydraulic actuator; a first pump flow adjustment device installed in the first line, the first pump flow adjustment device being configured to adjust; a first hydraulic accumulator for accumulating the hydraulic fluid delivered from the first hydraulic pump; and a first accumulation flow adjustment device configured to adjust the flow of the hydraulic fluid from the first hydraulic pump to the first hydraulic accumulator. The hydraulic drive system further comprises a first accumulation flow supply device configured to supply the hydraulic fluid accumulated in the first hydraulic accumulator to the first hydraulic actuator via a second line different from the first line.