Controlled Hydraulic Recirculation for Turboprop Pump Cooling
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Solution Overview
Problem
The existing hydraulic circuits for aircraft turboprops with recirculation systems require overdesigning the pump to compensate for recirculated fluid flow, leading to inefficiencies and unnecessary energy loss, as the recirculation circuit operates even when the propeller pitch actuation system is active.
Innovation Solution
A hydraulic circuit with a valve that selectively opens and closes the recirculation circuit based on fluid pressure in the supply pipe, ensuring that all pump output fluid is directed to the actuation system during operation and recirculated only when the system is idle, using a controlled check valve to manage pressure and flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the recirculation circuit is continuously open to ensure pump lubrication and cooling, then the pump is properly lubricated and cooled, but the pump must be overdesigned to compensate for recirculated flow, leading to energy loss
Solution Approach 1:
The recirculation valve transitions from a static always-open state to a dynamic state that opens or closes based on actuation system operation. When the actuation system is inactive, the valve opens to maintain pump lubrication and cooling. When the actuation system is active, the valve closes to direct all pump flow to the actuators, eliminating the need for pump overdesign and reducing energy loss.
2Loss of energy
If the recirculation circuit is closed during actuation operation to supply all fluid flow to actuators, then energy loss is reduced, but pump lubrication and cooling may be insufficient
Solution Approach 1:
The system dynamically switches between two operational modes: in idle mode, the recirculation valve opens to maintain pump lubrication and cooling; in actuation mode, the valve closes to maximize flow to actuators. This dynamic switching ensures that pump protection is maintained when needed while eliminating energy waste when actuation is active.
3Reliability
If the pump is overdesigned to compensate for recirculation flow, then continuous lubrication and cooling are ensured, but device complexity and size increase
Solution Approach 1:
Instead of designing the pump for maximum continuous flow (overdesign), the system uses a dynamically controlled valve to manage flow distribution. The pump can be sized for the actual actuation requirements, and the valve ensures continuous lubrication and cooling by opening the recirculation path only when actuators are not active, thereby reducing device complexity while maintaining reliability.
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 ensures continuous lubrication and cooling of the pump while maximizing fluid flow to the actuation system, preventing overdesign and reducing energy loss by optimizing fluid distribution based on operational needs.
Implementation Method 1
the valve can change state as a function of the fluid pressure in a component supply pipe, connecting the component to the pump
Implementation Method 2
the control device is a controlled check valve that closes off the supply pipe when the component is not in operation, to increase the pressure in a segment of the supply pipe upstream from the check valve
Data Source
AI summary
The invention relates to a hydraulic circuit (10) for an aircraft turboprop comprising a hydraulic fluid tank (16), a pump (14), a component (12) that is supplied with fluid pressurised by the pump (14) and that is selectively put into operation, and a fluid recirculation circuit (20) between the pump discharge (14) and the tank (16) characterised in that it comprises a valve (22) located in the recirculation circuit (20), that is capable of closing the recirculation circuit (20) when the component (12) is not in operation and is capable of opening the recirculation circuit (20) when the component is in operation.