Construction Machine Hydraulics With Shared Unloading Valve Control
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Solution Overview
Problem
Existing hydraulic systems in construction machines require a dedicated solenoid valve to invalidate operations on operation devices, which is inefficient and potentially unreliable.
Innovation Solution
A hydraulic system configuration where a single solenoid proportional valve, connected to an unloading valve and a switching valve, uses secondary pressure to control the opening area and switching of the unloading valve, allowing it to invalidate operations without a dedicated solenoid valve for invalidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated solenoid valve is used to invalidate operations on operation devices, then the system can reliably stop hydraulic oil supply to solenoid proportional valves, but the device complexity increases and the system becomes less efficient
Solution Approach 1:
The patent combines the function of invalidating operation devices with the unloading valve that already exists in the hydraulic system. The unloading valve's solenoid proportional valve is made to perform dual functions: both unloading hydraulic oil from the main pump and invalidating operations on operation devices by controlling hydraulic oil supply to control valves. This merging eliminates the need for a dedicated solenoid valve, reducing device complexity while maintaining reliability.
Solution Approach 2:
The unloading valve is designed with multi-functionality, serving both as an unloading valve for the main pump and as a validation/invalidation valve for operation devices. By making the solenoid proportional valve of the unloading valve control both the unloading function and the operation validation function, the system achieves universal functionality with a single valve, improving efficiency and reducing complexity.
2Ease of operation
If a dedicated solenoid valve is added to invalidate operations, then operational control is improved, but the cost and number of components increase
Solution Approach 1:
The patent merges the operation validation control function into the existing unloading valve system. The solenoid proportional valve of the unloading valve is controlled by the controller to both unload hydraulic oil and to validate/invalidate operations on operation devices. This combining of functions reduces the total number of valves from two (unloading valve plus dedicated invalidation valve) to one (multi-functional unloading valve).
Solution Approach 2:
The unloading valve is designed to perform multiple functions: unloading hydraulic oil from the main pump during idle periods and controlling the validation/invalidation of operation devices during operation. This multi-functionality eliminates the need for separate dedicated valves, reducing component quantity while maintaining full operational control capability.
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 eliminates the need for a dedicated solenoid valve, enhances reliability by allowing the system to switch between operational states based on secondary pressure, and maintains maximum unloading valve opening area until pilot pressure exceeds a setting value, reducing the risk of machine shutdown due to failures.
Implementation Method 1
an unloading valve provided on a line extending to a tank, the line being branched off from a supply line that connects between the main pump and the control valves, the unloading valve including a pilot port and being a valve whose opening area is at a maximum when none of the operation devices are operated; a second solenoid proportional valve connected to the pilot port of the unloading valve by a secondary pressure line
Implementation Method 2
a switching valve interposed between the auxiliary pump and the first solenoid proportional valves, the switching valve including a pilot port connected to the secondary pressure line by a pilot line, the switching valve switching between a closed position and an open position in accordance with a pilot pressure led to the pilot port
Data Source
AI summary
A hydraulic system of a construction machine includes: control valves interposed between a main pump and hydraulic actuators; and first solenoid proportional valves connected to pilot ports of the control valves. The hydraulic system further includes: an unloading valve including a pilot port; and a second solenoid proportional valve connected to the pilot port of the unloading valve by a secondary pressure line and connected to an auxiliary pump by a primary pressure line. A switching valve including a pilot port connected to the secondary pressure line by a pilot line is interposed between the auxiliary pump and the first solenoid proportional valves.