Bidirectional Electric Pump for Hybrid Powertrain Hydraulic Fluid Management
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Solution Overview
Problem
Hybrid electric vehicles require a modular powertrain module that can be installed between various engines and transmissions, with a hydraulic system that ensures continuous hydraulic fluid supply to prevent air ingestion and maintain line pressure, especially when the engine is off or the vehicle is stationary on a slope.
Innovation Solution
A hydraulic system with a bidirectional electric pump that supplies fluid from a module sump to a transmission sump when line pressure is unavailable and vice versa, ensuring reliable fluid circulation and preventing air ingestion by reversing pump direction based on fluid volume and vehicle inclination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is turned off to conserve fuel while the vehicle is stopped, then fuel efficiency is improved, but line pressure becomes unavailable and hydraulic fluid circulation is disrupted
Solution Approach 1:
An electric pump is introduced as an intermediary device to maintain hydraulic fluid circulation when the engine is off. The electric pump can be independently activated to supply line pressure without requiring engine operation, thus resolving the conflict between fuel conservation and hydraulic system reliability.
Solution Approach 2:
The system changes the operational parameters of the hydraulic pump from engine-driven (mechanical) to electrically-driven. This allows the pump to operate independently of engine status, enabling line pressure maintenance during engine-off conditions while preserving fuel efficiency during normal operation.
2Quantity of substance
If the vehicle is stopped on a grade whose slope causes fluid to be retained in the module sump, then fluid retention occurs in the module sump, but the transmission sump volume becomes low enough to risk air ingestion into the transmission pump inlet
Solution Approach 1:
The electric pump reverses the normal fluid flow direction by pumping fluid from the module sump back to the transmission sump when needed. This inverted flow compensates for gravity-induced fluid retention on grades, ensuring the transmission sump maintains adequate fluid volume to prevent air ingestion.
Solution Approach 2:
The system incorporates sensors to monitor fluid volume in the transmission sump and vehicle inclination. When the fluid volume drops below a threshold or a steep grade is detected, the control system activates the electric pump to restore proper fluid levels, creating a feedback loop that prevents air ingestion.
3Adaptability or versatility
If a modular powertrain module is designed to be installed between various engines and transmissions, then versatility is improved, but hydraulic system compatibility and fluid supply reliability become more complex
Solution Approach 1:
The electric pump is designed as a universal component that can interface with different engine and transmission configurations. It provides a standardized hydraulic fluid supply solution that works across multiple powertrain combinations, simplifying the overall system architecture despite the variety of compatible engines and transmissions.
Solution Approach 2:
The hydraulic system is segmented into independent zones (module sump and transmission sump) with the electric pump serving as a controllable transfer mechanism between them. This segmentation allows each zone to be optimized for its specific function while the pump provides flexible fluid management to maintain system 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
The system maintains reliable hydraulic fluid circulation and line pressure, preventing air ingestion and ensuring efficient operation of the powertrain across different engine and transmission configurations, enhancing fuel efficiency and vehicle performance.
Implementation Method 1
a pump that supplies fluid from the second sump to the line pressure source when the source of line pressure is unavailable, and supplies fluid from the first sump to the second sump when fluid volume in the second sump is low
Data Source
AI summary
A hydraulic system for a vehicle powertrain includes a module including a clutch, an electric machine and a first sump, a transmission including a line pressure source and a second sump, and a pump that supplies fluid from the first sump to the line pressure source when the source of line pressure is unavailable, and supplies fluid from the first sump to the second sump when fluid volume in the second sump is low.