Transmission Pump Assembly With Multi-Pump Flow Switching
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Solution Overview
Problem
Conventional transmission systems with fixed ratio pumps experience flow losses and inefficiencies at varying engine speeds, and electrification challenges due to traction motors' inability to replicate engine-driven hydraulic functionality, especially at standstill, while complex valve control strategies increase computing resource usage and degradation risks.
Innovation Solution
A transmission system with an electric motor rotationally coupled to multiple fixed displacement pumps and a directional control valve, where the controller selectively operates the valve based on operating conditions to manage fluid flow between lubrication and actuation circuits, inhibiting fluid communication during non-shift events to reduce losses and increase efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If variable displacement pumps are used to reduce flow losses and increase system efficiency, then energy efficiency is improved, but device complexity and likelihood of component degradation increase
Solution Approach 1:
The pump system is segmented into multiple fixed displacement pumps (first pump, second pump, third pump) with distinct functions. The first and second pumps deliver fluid to the lubrication circuit, while the third pump delivers fluid to the actuation circuit. This segmentation allows each pump to be optimized for its specific function using simpler fixed displacement design, avoiding the complexity of variable displacement mechanisms while maintaining efficiency.
Solution Approach 2:
The electric motor serves multiple functions: it drives all three pumps and can operate independently of engine speed, providing hydraulic functionality across the entire operating range including standstill conditions. This multi-functionality replaces the need for complex variable displacement mechanisms while achieving similar efficiency goals.
2Adaptability or versatility
If traction motors are used to replace engine-driven pumps in electrified powertrains, then adaptability to electrification is improved, but hydraulic functionality at standstill is lost
Solution Approach 1:
The electric motor is designed with universal functionality to drive multiple pumps serving different hydraulic circuits. It can operate at various speeds including zero RPM, ensuring hydraulic functionality is maintained during standstill and low-speed operations, which is critical for electrified powertrains where the traction motor may not always be rotating.
3Adaptability or versatility
If complex valve control strategies are used to manage fluid flow, then system adaptability is improved, but computing resource usage and system complexity increase
Solution Approach 1:
The fluid delivery system is segmented into dedicated circuits with specific pumps for specific functions (lubrication and actuation). This segmentation simplifies control requirements compared to a single complex variable displacement pump, as each fixed displacement pump can be controlled independently based on basic speed and flow requirements, reducing the need for complex valve control strategies.
Solution Approach 2:
The system achieves adaptability through dynamic control of the electric motor speed rather than complex valve strategies. By varying the motor speed, the flow rate to each pump can be adjusted dynamically to meet changing hydraulic demands, providing system flexibility with simpler control logic.
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 enhances transmission longevity and performance by reducing flow losses and component degradation, achieving efficient hydraulic performance with simplified pump design and reduced computing resource usage.
Implementation Method 1
an electric motor rotationally coupled to a first pump, a second pump, and a third pump via a drive shaft
Implementation Method 2
pumps which deliver oil or other fluid to selected systems in the transmission
Data Source
AI summary
A transmission system is provided. The transmission system includes an electric motor rotationally coupled to a first pump, a second pump, and a third pump via a drive shaft, where an output of the first pump is in fluidic communication with a lubrication circuit and where an output of the third pump is in fluidic communication with an actuation circuit. The transmission system further includes a valve fluidly coupled to the output of the first pump and an output of the second pump and a controller including instructions stored in non-transitory memory that when executed during a first operating condition, cause the controller to selectively operate the valve based on a change in one or more operating conditions in the transmission system.