Load Sense Valve Venting via Single Seat Check
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Solution Overview
Problem
Conventional load sense valves in mobile systems face issues with constant flow loss and increased costs due to venting mechanisms, particularly at high pressures, and require complex and expensive shuttle systems to manage load sense signals effectively.
Innovation Solution
The implementation of a single seat check valve design with a separate load sense passage that interacts with undercut control spools, allowing proper venting when spools are in neutral and blocking vent connection when shifted, preventing pressure loss and de-stroking of the pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single seat check valve is used to transmit the highest pressure to the pump LS signal line, then the response speed is faster and the structure is simpler, but the LS signal must be vented constantly which causes flow loss and pressure loss especially at high pressure
Solution Approach 1:
The venting action is performed in advance when the spool is in neutral position, allowing the LS passage to be connected to tank. When the spool shifts to flow position, the vent path is automatically blocked by the spool body, trapping pressure in the circuit and preventing further flow loss
2Device complexity
If a single seat check valve with constant venting is used, then the structure is simpler, but the LS signal becomes unstable and inconsistent due to constant flow loss
Solution Approach 1:
The venting state transitions from static constant venting to dynamic conditional venting. The spool position dynamically controls the vent path: open when neutral, closed when actuated. This dynamic behavior maintains LS signal stability by eliminating constant flow loss while keeping the circuit simple
3Reliability
If a shuttle check system is used to manage LS signal, then the signal can be vented through internal passages, but the system becomes more complicated and expensive with higher pressure drop
Solution Approach 1:
The complex shuttle check system and its internal venting passages are extracted and replaced with a simpler single seat check valve design. The venting function is achieved through the spool's own structure rather than a separate shuttle mechanism, reducing system complexity and pressure drop while maintaining signal management 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 solution provides a stable and consistent load sense signal with reduced manufacturing costs and eliminates the need for constant flow loss, making the system less expensive and more efficient than conventional systems.
Implementation Method 1
a first load sense check valve disposed between the first hydraulic valve and the load sense passage and configured to allow flow from a flow portion of the first hydraulic valve to the load sense passage and block flow from the load sense passage to the flow portion of the first hydraulic valve
Implementation Method 2
in the neutral position, the first hydraulic valve closes the flow portion of the first hydraulic valve, preventing flow from a flow inlet of the first hydraulic valve towards a first work port of the first hydraulic valve, and opens a load sense portion, allowing flow from the load sense passage towards a drain passage
Data Source
AI summary
A load sense passage in a load sense hydraulic system may be vented by allowing flow from the load sense passage to a reservoir via a drain passage when a first flow control valve is in a neutral position. This venting may be prevented by preventing flow from the load sense passage to a reservoir via the drain passage when the first flow control valve is in a flow-allowing position.