Dual Oil Pump Switching Valve for Stable Supply Pressure
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Solution Overview
Problem
The existing working fluid supply systems face instability due to sudden variations in supply pressure when switching between pumps, leading to potential operational issues with fluid apparatuses.
Innovation Solution
A system comprising a first and second pump driven by a common source, a valve device that allows communication between discharge and supply passages, and a control unit that adjusts the valve's communication state based on required flow amounts and predicted pressure variations, with a switching time set to manage these changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the supply target of the working fluid from the sub-pump is switched to the discharge side of the main pump, then the amount of working fluid supplied to the fluid apparatus is increased suddenly to increase supply pressure, but the fluid apparatus cannot be operated stably
Solution Approach 1:
The switching valve transitions through an intermediate state before reaching the final discharge side connection state. This preliminary action of gradually opening the valve to the discharge side allows the working fluid to be introduced progressively, preventing sudden pressure increases and enabling stable operation of the fluid apparatus while still achieving the required increase in working fluid supply amount.
2Productivity
If the supply target of the working fluid from the sub-pump is switched from the discharge side to the suction side of the main pump, then the amount of the working fluid supplied to the fluid apparatus is decreased suddenly to reduce the supply pressure, but the fluid apparatus cannot be operated stably
Solution Approach 1:
The switching valve transitions through an intermediate state before reaching the final suction side connection state. This preliminary action of gradually closing the valve from the discharge side allows the working fluid supply to be reduced progressively, preventing sudden pressure decreases and enabling stable operation of the fluid apparatus while still achieving the required decrease in working fluid supply amount.
3Productivity
If the communication state of the valve device is switched instantaneously from the first communication state to the second communication state, then the supply pressure varies significantly, but the switching time is extended
Solution Approach 1:
The switching process is divided into multiple stages: an intermediate state where the switching valve is partially opened to the discharge side, and a final state where it is fully opened. This segmentation of the switching process allows the communication state to change gradually through the intermediate state, reducing supply pressure variations while still achieving the required switching functionality.
Data Source
AI summary
A working fluid supply system is provided with: a first oil pump and a second oil pump driven by an engine; a switching valve configured to cause a discharge passage of the second oil pump to communicate with at least one of a supply passage and a first drain passage; and a controller configured to switch the switching valve. The controller is configured to switch the switching valve by spending a switching time that is set in accordance with a degree of pressure variation predicted to be caused in the supply passage when the switching valve is switched instantaneously.