Boom Cylinder Hydraulic Holding Control for Stable Excavator Lowering
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Solution Overview
Problem
Existing excavator systems face challenges in simultaneously preventing boom dropping and appropriately adjusting the pressure in the bottom-side oil chamber of the boom cylinder, leading to unstable actions such as lifting and vibrating, which are not intended by the operator.
Innovation Solution
The implementation of a hydraulic mechanism with a control device that releases and controls the pressure in the boom cylinder's oil passage, ensuring the acting velocity in the lowering direction is less than or equal to a predetermined reference, thereby stabilizing the excavator's operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic oil is held in the bottom-side oil chamber of the boom cylinder to prevent dropping, then boom dropping is prevented, but the pressure in the bottom-side oil chamber cannot be adjusted appropriately, causing unstable actions
Solution Approach 1:
A second hydraulic mechanism section is introduced as an intermediary component in the oil passage between the bottom-side oil chamber and the first hydraulic mechanism section. This intermediary section includes a valve that can open or close the oil passage, enabling controlled pressure adjustment while maintaining the primary function of preventing boom dropping. The intermediary mechanism allows selective communication between oil chambers, resolving the contradiction between holding oil for stability and allowing pressure adjustment.
2Reliability
If the second hydraulic mechanism section is closed to hold hydraulic oil, then boom dropping is prevented, but unstable actions such as lifting and vibrating occur
Solution Approach 1:
The second hydraulic mechanism section is designed with dynamic controllability, allowing the valve to switch between closed and open states based on operational conditions. The control device dynamically adjusts the valve state to maintain boom position stability while preventing unstable actions. This dynamic approach resolves the contradiction by adapting the system state rather than maintaining a fixed closed state.
Solution Approach 2:
The control device monitors the state of the boom and the operation state of attachments, and based on this feedback, determines whether to open or close the second hydraulic mechanism section. When unstable actions are detected, the control device opens the valve to release hydraulic oil and stabilize the excavator. This feedback mechanism resolves the contradiction by continuously adjusting the system based on actual operational conditions.
3Stability of the object's composition
If the second hydraulic mechanism section is opened to adjust pressure, then unstable actions are reduced, but boom dropping risk increases
Solution Approach 1:
The second hydraulic mechanism section acts as a controlled intermediary that can selectively open or close the oil passage. When opening to reduce unstable actions, it does so in a controlled manner that maintains sufficient pressure to prevent boom dropping. The intermediary valve provides fine-grained control over oil flow, resolving the contradiction between releasing pressure for stability and maintaining pressure for boom support.
4Device complexity
If a simple holding mechanism is used, then device complexity is low, but pressure control capability is insufficient
Solution Approach 1:
The hydraulic mechanism is segmented into two distinct sections: the first hydraulic mechanism section for primary boom control and the second hydraulic mechanism section for pressure adjustment. The second section includes a valve mechanism that can independently control oil passage communication. This segmentation allows the system to maintain relative simplicity while gaining enhanced pressure control capability through the added valving functionality.
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 effectively prevents boom dropping and reduces unstable actions like rear portion lifting and vibrating, enhancing the operational stability and control of the excavator.
Implementation Method 1
hold a hydraulic oil in a bottom-side oil chamber of the boom cylinder
Implementation Method 2
control a released state so that an acting velocity in a lowering direction of the boom is less than or equal to a predetermined reference
Data Source
AI summary
An excavator includes a hydraulic oil holding circuit that is provided in an oil passage between a bottom-side oil chamber of a boom cylinder and a control valve and is closed when the boom is not lowered, and a controller. The controller releases a closed state of the hydraulic oil holding circuit when the excavator is in a predetermined unstable state, and controls a released state so that an acting velocity in a lowering direction of the boom becomes less than or equal to a predetermined reference.