Hydraulic Drive Apparatus Cavitation Prevention Regeneration Efficiency
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Solution Overview
Problem
Existing hydraulic control systems for construction machines face challenges in preventing cavitation and improving regeneration efficiency during slewing deceleration, with known solutions either reducing regeneration efficiency or requiring costly and complex additional facilities.
Innovation Solution
A hydraulic drive apparatus with a regenerative motor, hydraulic brake circuit, and a regeneration-tank-line selector valve that dynamically routes regeneration discharge fluid through a back pressure valve during slewing deceleration to prevent cavitation and optimize regeneration efficiency, while bypassing the back pressure valve during non-deceleration to enhance rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the regenerative motor discharge fluid is returned to the tank through the back pressure valve during slewing deceleration, then cavitation is prevented, but regeneration efficiency is reduced due to back pressure
Solution Approach 1:
The system dynamically switches between two return paths for regenerative motor discharge fluid based on operational conditions. During slewing deceleration, fluid returns through the back pressure valve to prevent cavitation. During normal operation, fluid returns directly to the tank to maximize regeneration efficiency. This dynamic adaptation resolves the contradiction by optimizing the system for different operational states.
Solution Approach 2:
The return path for regenerative motor discharge fluid is segmented into two separate routes: one through the back pressure valve and another direct return path to the tank. The regeneration tank line selector valve enables switching between these segmented paths, allowing the system to choose the optimal route based on whether cavitation prevention or regeneration efficiency is the priority.
2Loss of energy
If a direct return line is added for regeneration discharge fluid to bypass the back pressure valve, then regeneration efficiency is improved, but facility complexity increases
Solution Approach 1:
The regeneration tank line selector valve serves multiple functions: it acts as a switching mechanism between two return paths, provides cavitation prevention during deceleration, and optimizes regeneration efficiency during normal operation. By making this single component multi-functional, the system achieves the desired performance without proportionally increasing overall facility complexity.
Solution Approach 2:
The regeneration tank line selector valve acts as an intermediary component that manages the flow of regenerative motor discharge fluid between two return paths. This intermediary device enables the system to switch between cavitation prevention mode and efficiency optimization mode, resolving the contradiction between regeneration efficiency and facility complexity by providing intelligent flow management.
3Reliability
If back pressure is applied to the regenerative motor during non-deceleration operation, then cavitation is prevented, but rotational speed and regeneration efficiency are reduced
Solution Approach 1:
The system dynamically adjusts the back pressure applied to the regenerative motor based on operational conditions. During slewing deceleration, back pressure is applied to prevent cavitation. During normal operation, back pressure is removed to maximize rotational speed and regeneration efficiency. This dynamic adjustment resolves the contradiction by applying back pressure only when necessary.
Solution Approach 2:
Instead of continuously applying back pressure to prevent cavitation, the system applies back pressure partially and selectively only during slewing deceleration when cavitation risk exists. This partial action approach prevents cavitation when needed while avoiding the performance penalty of continuous back pressure application, thereby maintaining high rotational speed during normal operation.
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
The apparatus effectively prevents cavitation and improves regeneration efficiency without increasing facility costs or complexity, by using a regeneration-tank-line selector valve to manage fluid flow based on slewing deceleration states and pressure conditions.
Implementation Method 1
a back pressure valve provided in the makeup line and configured to generate back pressure in the makeup line
Implementation Method 2
a regenerative motor driven by a part of the hydraulic fluid discharged from the hydraulic actuators to perform regenerative action
Implementation Method 3
a hydraulic brake circuit including a relief valve and configured to perform anti-cavitation action for returning the hydraulic fluid on a meter-out side of the slewing motor to a meter-in side
Data Source
AI summary
Provided is a hydraulic drive apparatus for a construction machine capable of achieving both of cavitation prevention and improvement of regeneration efficiency. The apparatus includes a regenerative motor (47) configured to regenerate energy of hydraulic fluid discharged from a slewing motor (33), a first regeneration tank line (61) for returning regeneration discharge fluid from the regenerative motor (47) to a tank (T) through a back pressure valve (45) which is provided in a makeup line (44), a second regeneration tank line (62) for returning the regeneration discharge fluid directly to the tank (T) so as to bypass the back pressure valve (45), a regeneration-tank-line selector valve (63), and a regeneration-tank-line-selection control section (51) configured to shift the regeneration-tank-line selector valve (63) to pass the regeneration discharge fluid through the first regeneration tank line (61) during slewing deceleration and otherwise through the second regeneration tank line (62).