Hydraulic Latching Circuit for Tractor Implement Sequencing
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Solution Overview
Problem
Agricultural tractor hydraulic systems face issues with heat dissipation and sequencing challenges when operating high-capacity equipment, particularly with continuous pressure application causing overheating and improper sequencing of wing and center frame lifts/lowers, and existing load sense systems lack control and sequencing mechanisms without electrical signals or power beyond systems.
Innovation Solution
The implementation of a hydraulic latching circuit with dual-pilot-operated directional valves and sequencing valves that activate and deactivate load sense power based on the selective control valve's positions, ensuring proper sequencing and down force control without electrical signals, and allowing operation with or without power beyond systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous pressure is applied through the selective control valve to operate high capacity equipment, then the equipment can function properly, but the hydraulic system overheats and consumes extra engine power
Solution Approach 1:
The patent applies periodic action by using a load sense system that activates down force pressure only when needed (when the implement is in the down position) rather than maintaining continuous pressure. The hydraulic circuit allows the pump to operate at lower pressure during implement lift, and only increases pressure when the implement reaches the down position, creating a periodic pressure application pattern that reduces overall heat generation while maintaining equipment functionality
2Ease of operation
If load sense pressure is communicated to the tractor during engine startup, then the down force system can be controlled, but it creates tractor starting issues under certain circumstances
Solution Approach 1:
The patent applies preliminary action through a latching valve that prevents load sense pressure from being communicated to the tractor during engine startup before the engine is fully operational. The latching valve remains closed during startup conditions and only opens after the engine is running, thereby preliminarily blocking the harmful pressure communication that would otherwise cause starting issues, while still allowing down force control functionality when the engine is properly running
3Ease of operation
If additional valve components are added to control down pressure sequencing, then proper sequencing of wing and center frame lifts/lowers can be achieved, but the device complexity increases
Solution Approach 1:
The patent applies the intermediary principle by using a latching valve as a mediator between the load sense system and the implement hydraulic circuit. This single intermediary component enables proper sequencing of wing and center frame operations by controlling when load sense pressure is applied, without requiring multiple complex valve components. The latching valve acts as an intelligent gateway that simplifies the overall circuit design while achieving the desired sequencing 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
The solution reduces heat production, conserves fuel, and ensures correct sequencing of implement lifts and lowers by managing load sense pressure and fluid flow dynamically, enhancing operational efficiency and control.
Implementation Method 1
latching valve means in the power beyond supply connection for opening and closing the connection, the latching valve means operable to close the connection until after fluid pressure from the selective control valve has been applied to the second end of the wing cylinder structure
Implementation Method 2
first sequencing valve to direct fluid to the first end of the wing cylinder structure then to the first end of the center frame cylinder structure when the SCV is in the first open position
Data Source
Figure 1
Figure 2
AI summary
A hydraulic implement system (100, 200) is provided that allows a load-sense power source (124, 224) to be activated and deactivated depending on a SCV (126, 226) function. The load sense power source (124, 224) is activated when wing cylinder structures (104, 204) are fully extended to maintain proper down force on the wings. It remains activated or latched when the SCV (126, 226) is returned to neutral. It is deactivated or unlatched when the wing cylinder structures (104, 204) are retracted. Two circuits have been devised to accomplish this latching function. Both of these latching circuits can be used with a sequencing circuit.