Auxiliary Pump Priming Control for Hybrid Transmissions
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Solution Overview
Problem
The electrically-driven auxiliary hydraulic pressure pump in vehicle transmissions can lose its prime due to air entrainment, incomplete servicing, or plumbing issues, leading to unreliable engine start-stop behavior and potential customer dissatisfaction.
Innovation Solution
A method is implemented to monitor fluidic pressures at multiple locations in the hydraulic circuit and command the electrically-driven auxiliary hydraulic pressure pump to an elevated voltage when the internal combustion engine is shut off and proper pressure levels are not registered, ensuring the pump is re-primed and maintaining reliable operation by discontinuing the boosted voltage when proper pressure levels are achieved or when the engine is restarted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the auxiliary pump operates at normal voltage during engine-off, then energy consumption is reduced, but hydraulic pressure may drop below proper levels causing prime loss
Solution Approach 1:
The system dynamically adjusts the auxiliary pump voltage based on real-time hydraulic pressure conditions. During engine-off, the controller monitors pressure sensors and automatically boosts pump voltage when pressure drops below threshold levels, then reduces voltage when pressure is adequate, creating a dynamic response that balances energy savings with pressure maintenance
Solution Approach 2:
The system implements a feedback control loop where pressure sensors continuously monitor hydraulic pressure in the transmission system, and the controller uses this feedback to determine when to activate or deactivate the auxiliary pump voltage boost, ensuring pressure is maintained only when necessary
2Reliability
If the auxiliary pump voltage is boosted continuously during engine-off, then hydraulic pressure is maintained, but energy consumption increases
Solution Approach 1:
Instead of continuous voltage boosting, the system applies periodic or conditional voltage boosts only when pressure sensors detect that hydraulic pressure has dropped below acceptable thresholds. The controller alternates between normal and boosted voltage states based on pressure conditions, reducing overall energy consumption while maintaining pressure when needed
Solution Approach 2:
The system changes the electrical parameter (voltage) of the auxiliary pump based on hydraulic pressure conditions. By adjusting the voltage parameter from normal to boosted levels only when necessary, the system optimizes the balance between maintaining hydraulic pressure and minimizing energy consumption
3Speed
If the engine is restarted immediately after shutdown, then responsiveness is improved, but the auxiliary pump may not be re-primed causing pressure dips
Solution Approach 1:
The system performs preliminary action by monitoring hydraulic pressure during the brief interval between engine shutdown and restart. If pressure drops indicate prime loss, the controller pre-activates the auxiliary pump at boosted voltage before engine restart completes, ensuring pressure is already stabilized when the engine comes back online
Solution Approach 2:
The system maintains continuous monitoring of hydraulic pressure throughout the engine stop-start cycle. The pressure monitoring and auxiliary pump control operate continuously to ensure uninterrupted hydraulic pressure stability, bridging the gap between engine shutdown and restart without allowing pressure dips
4Measurement precision
If pressure monitoring is implemented at multiple locations, then detection accuracy is improved, but system complexity increases
Solution Approach 1:
The system segments the hydraulic circuit into multiple monitoring zones by placing pressure sensors at different critical locations. Each sensor monitors a specific segment of the hydraulic system, allowing the controller to identify the location and nature of pressure issues more accurately without requiring a single complex monitoring system
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 approach ensures reliable and consistent engine start-stop behavior by maintaining hydraulic pressure in the transmission, reducing the likelihood of fault codes and customer dissatisfaction, and minimizing warranty costs.
Implementation Method 1
an electrically-driven auxiliary hydraulic pressure pump can be implemented to provide hydraulic pressure
Implementation Method 2
boost hydraulic pressure and minimize pressure dips
Data Source
AI summary
A method and article of manufacture is provided to control an automatic transmission which includes a hydraulic fluid circuit having an electrically-driven auxiliary hydraulic pressure pump. It includes determining the internal combustion engine is shut off during vehicle operation, and monitoring fluidic pressure at a plurality of locations in the hydraulic circuit. Operation of the electrically-driven auxiliary hydraulic pressure pump is commanded to an elevated voltage level when the engine is shut off and the fluidic pressures fail to register substantially proper pressure levels. It includes discontinuing operation of the electrically-driven auxiliary hydraulic pressure pump when the engine is subsequently commanded on, or when an elapsed measure of time has passed, or when the monitored fluidic pressures register substantially proper pressure levels.