Hydraulic Control Device Bypass-Cutting Valve Heat Prevention
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Solution Overview
Problem
In hydraulic excavators, the unified bleed-off control method is prone to failures, leading to operational hindrances and heat generation when the unified bleed-off valve malfunctions, especially due to issues like broken wires in the control system, which affects the operation of actuators and increases costs and complexity.
Innovation Solution
A hydraulic control device with control valves, hydraulic actuators divided into groups, central bypass paths, and bypass-cutting valves that automatically switch to open or close central bypass lines when the unified bleed-off valves are not operated, ensuring oil unloading and preventing heat generation, while maintaining actuator operation even during failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a unified bleed-off valve is used to control multiple control valves, then control flexibility is improved, but reliability deteriorates because the system becomes vulnerable to single-point failures that can halt entire machine operations
Solution Approach 1:
The invention divides the unified bleed-off control system into multiple independent groups, each with its own bleed-off valve and control mechanism. This segmentation ensures that a failure in one group does not affect other groups, maintaining system reliability while preserving control flexibility through independent group management.
Solution Approach 2:
The invention applies different control characteristics to different groups of control valves based on their specific requirements. Each group can have customized bleed-off control parameters, allowing optimal performance for each actuator type while maintaining overall system flexibility and reducing the impact of localized failures.
2Manufacturing precision
If bleed-off paths are extended in control valves to improve bleed-off control, then control precision is improved, but device complexity increases due to longer valve length and assembly difficulties
Solution Approach 1:
The invention transitions from extending bleed-off paths in the spool shaft direction (one dimension) to implementing bleed-off control through separate control stages and pressure regulation mechanisms (additional dimensions). This dimensional change achieves precise bleed-off control without increasing valve length or assembly complexity.
Solution Approach 2:
The invention introduces intermediate control elements such as pilot pressures and control stages that mediate the bleed-off control process. These intermediaries enable precise control of oil flow without requiring long bleed-off paths, thereby maintaining compact valve design while achieving high control precision.
3Adaptability or versatility
If electronic control is used to operate the unified bleed-off valve, then control flexibility is improved, but reliability deteriorates due to vulnerability to electrical failures and wire breaks
Solution Approach 1:
The invention incorporates redundant control mechanisms and fail-safe designs that prepare for potential electronic failures in advance. Multiple control paths and backup systems are built in before failures occur, ensuring that electronic control flexibility is maintained while protecting against reliability issues from wire breaks or controller failures.
4Productivity
If hydraulic actuators are divided into separate groups driven by separate pumps, then productivity is improved through efficient flow distribution, but device complexity increases due to additional switching valves and circuit complexity
Solution Approach 1:
The invention designs the switching valve and control circuit to perform multiple functions: distributing oil to different actuator groups, enabling simultaneous operation, and providing bleed-off control. This multi-functionality achieves efficient flow distribution to multiple groups without proportionally increasing circuit complexity, as the same components serve multiple purposes.
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 solution ensures reliable operation of hydraulic actuators and prevents heat generation during unified bleed-off valve failures, simplifies the circuit structure, and reduces costs by integrating bypass-cutting valves into a common valve, ensuring efficient oil distribution and actuator functionality.
Implementation Method 1
hydraulic control device for working machines such as hydraulic excavators
Data Source
AI summary
A hydraulic control device for a working machine includes control valves; hydraulic actuators controlled by corresponding control valves and divided into groups; unified bleed-off valves disposed on discharge lines of first and second hydraulic pumps; central bypass paths provided in the control valves, the central bypass paths of each group being connected in tandem so as to form a central bypass line; and bypass-cutting valves disposed on the central bypass lines, the bypass-cutting valves being automatically switched so as to open the central bypass lines when the unified bleed-off valves are not operated.