Supplemental Hydraulic Pump Load-Sense Flow Control at Low Engine Speed
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Solution Overview
Problem
Current tractor hydraulic systems experience reduced implement performance due to decreased hydraulic flow at lower engine speeds, leading to increased parasitic power losses from continuous operation of additional pumps at elevated pressure levels when additional flow is not needed.
Innovation Solution
A hydraulic system with a supplemental pump that operates in a standby condition at lower flow and pressure, switching to higher flow and pressure only when required, using a load sense circuit and valves to manage flow distribution between primary and supplemental circuits based on pressure differentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an additional pump operates continuously to provide hydraulic flow at lower engine speeds, then implement performance is maintained, but parasitic power losses increase due to continuous operation at elevated pressure levels
Solution Approach 1:
The supplemental pump is designed with variable displacement capability, allowing its flow output to dynamically adjust based on system demands. The pump can operate at different displacement levels (from minimum to maximum) depending on whether additional flow is needed, enabling it to transition between standby and active states efficiently
Solution Approach 2:
The system changes the operating parameters (pressure and flow) of the supplemental pump based on system conditions. When additional flow is not needed, the pump operates at low pressure and minimum flow; when needed, it increases to high pressure and maximum flow, optimizing energy efficiency across different operating conditions
2Quantity of substance
If the supplemental pump operates at higher flow and pressure continuously, then hydraulic flow availability is ensured, but energy efficiency decreases due to continuous high pressure operation
Solution Approach 1:
The supplemental pump operates intermittently rather than continuously, switching between standby (low flow) and active (high flow) states based on system demands. This periodic operation pattern ensures hydraulic flow availability when needed while minimizing energy consumption during non-critical periods
Solution Approach 2:
The supplemental pump is equipped with its own independent load sense circuit and control valves, allowing it to autonomously determine when additional flow is needed and self-regulate its operation without requiring external control signals, optimizing its energy usage based on real-time system conditions
3Device complexity
If load sense circuits are connected directly between primary and supplemental pumps, then flow distribution is simplified, but pressure imbalances cause improper operation of the supplemental pump
Solution Approach 1:
Isolated load sense circuits act as intermediary systems between the primary and supplemental pumps. These circuits use check valves and isolation valves to prevent direct pressure interaction while still allowing the supplemental pump to sense and respond to system load conditions independently, ensuring proper operation without pressure imbalances
Solution Approach 2:
The load sense circuits are segmented into separate, independent systems for the primary and supplemental pumps. This segmentation allows each pump to have its own pressure sensing and control pathway, preventing pressure imbalances from affecting the supplemental pump's operation while maintaining overall system coordination
Data Source
AI summary
A hydraulic system for a work vehicle includes a first pump providing a first flow in a first circuit having a first pressure. A first load sense circuit connected to a first load sensing compensator of the first pump. The first load sense circuit having a first load sense pressure. A supplemental pump provides a supplemental flow to a supplemental circuit having a supplemental pressure. A supplemental load sense circuit connected to a supplemental load sensing compensator of the supplemental pump. A first supplemental valve selectively enables flow from the first load sense circuit to the supplemental load circuit based in part on a first pressure differential between the first pressure and the first load sense pressure. A first valve selectively enables flow from the supplemental circuit to the first circuit when the supplemental pressure is equal to or greater than the first pressure.