Hydraulic Latching for Active Implement Down Force
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Solution Overview
Problem
Agricultural tractor hydraulic systems generate excessive heat and consume more fuel due to high pressure standby conditions in active down force systems, leading to potential overheating and starting issues, especially in tractors with marginal cooling systems and those without power beyond systems.
Innovation Solution
A hydraulic latching function is implemented using dual-pilot or single-pilot directional valves and check valves to control the load-sensed power source, allowing activation and deactivation based on the selective control valve position, preventing pressure buildup during tractor startup and enabling operation without power beyond or load sense lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hydraulic pump runs at high pressure standby condition during active down force system operation, then the system maintains ready-to-apply down force capability, but the system generates excessive heat and consumes more power
Solution Approach 1:
The system dynamically transitions between high pressure standby mode and load pressure mode based on operational needs. The selective control valve shifts between positions to activate the down force system only when required, allowing the hydraulic pump to operate at lower pressures during normal fan operation, thereby reducing heat generation while maintaining the ability to quickly apply down force when needed
Solution Approach 2:
The down force system operates in periodic cycles rather than continuous high pressure standby. The system activates the high pressure state only during brief periods when down force is actually applied to the implement, then returns to lower pressure operation, creating a periodic on-demand operation pattern that reduces overall heat generation and power consumption
2Reliability
If the hydraulic pump runs at high pressure standby condition, then the down force system is ready for immediate application, but fuel consumption increases
Solution Approach 1:
The hydraulic system dynamically adjusts its operating state based on actual down force requirements. The selective control valve enables transition between high pressure standby and load pressure modes, allowing the system to consume fuel efficiently during normal operation while maintaining the capability to quickly apply down force when needed, thereby reducing overall fuel consumption
Solution Approach 2:
The system uses the existing hydraulic circuitry and valve mechanisms to automatically manage pressure states without requiring external intervention. The selective control valve and directional valves work together to self-regulate the hydraulic pump's operating pressure based on system needs, eliminating the continuous high pressure standby that would increase fuel consumption
3Extent of automation
If load sense signal pressure is communicated to the tractor during engine startup, then the load-sensed power source can be activated, but tractor starting difficulties occur
Solution Approach 1:
The system is designed to prevent load sense signal pressure from being communicated to the tractor during engine startup before the hydraulic system is fully operational. The directional valves and hydraulic circuitry are configured to only activate the load-sensed power source after successful engine startup, eliminating starting difficulties while maintaining automatic activation capability once the system is running
Solution Approach 2:
The directional valves act as intermediaries between the load sense signal and the hydraulic pump activation. These valves control when and how the load sense pressure is communicated to the pump, preventing premature activation during startup while enabling automatic activation once the system is operational, thus resolving the conflict between automation and starting reliability
4Temperature
If additional valve components are added to the active down force circuit, then the system can operate below stall pressure and reduce heat generation, but device complexity increases
Solution Approach 1:
The selective control valve and directional valves are designed to perform multiple functions within the hydraulic circuit. These valves not only control the activation and deactivation of the down force system but also manage the transition between high pressure standby and load pressure modes, and coordinate the operation of rockshaft cylinders and down force circuits. By making these valves multi-functional, the patent reduces the need for additional specialized components, thereby limiting the increase in device complexity while achieving heat reduction through lower operating pressures
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 generation and fuel consumption by maintaining lower system pressures, prevents starting difficulties, and allows operation of down force circuits in tractors without power beyond systems, while ensuring controlled activation and deactivation of the load-sensed power source.
Implementation Method 1
a valve structure is provided in the power beyond fluid line to keep the fluid line closed when starting the tractor. This valve structure provides a hydraulic latching function that allows the load-sensed power source to be activated and deactivated depending on the SCV function.
Implementation Method 2
During implement lift, a check valve allows hydraulic flow from the cylinders to bypass the pressure reduction valve. The system therefore operates at lower pressure and lower power to produce less heat and increase fuel economy.
Data Source
AI summary
A load sense connection is provided between the implement rockshaft cylinders and the load-sensed power source. However, to avoid tractor starting difficulty, a valve structure is provided in the power beyond fluid line to keep the fluid line closed when starting the tractor. This valve structure provides a hydraulic latching function that allows the load-sensed power source to be activated and deactivated depending on the SCV function. The load-sensed power source is activated when the rockshaft cylinder(s) is fully extended and remains activated or latched when the SCV is returned to neutral. The load-sensed power source is deactivated or unlatched when the rockshaft cylinder is retracted.