Smart Relief Valve Control for Demand-Matched Transmission Pressure
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Solution Overview
Problem
Existing hydraulic systems in transmissions suffer from inefficiencies due to high pumping losses, incompatibility with various hydraulic devices, and inadequate pressure demand management, leading to suboptimal performance and increased torque absorption during engine cranking.
Innovation Solution
A hydraulic system with a boost pump, a relief valve, and multiple control valves, where a controller actively adjusts the relief valve based on aggregate hydraulic pressure demands to alter the boost pressure, ensuring efficient delivery of hydraulic fluid to various devices while minimizing pumping losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pump displacement is selected to meet maximum flowrate demands at design pressure, then the hydraulic devices can receive sufficient flowrate, but a relatively high amount of energy is wasted due to pumping losses as the hydraulic devices do not use all the oil provided by the pump at design pressure
Solution Approach 1:
The relief valve is dynamically controlled by adjusting its opening degree based on real-time hydraulic pressure demands of multiple devices. The controller receives pressure demand signals from various hydraulic devices and continuously adjusts the relief valve position to match supply pressure with actual demand, transitioning from a static design-pressure system to a dynamic demand-responsive system that minimizes energy waste while ensuring sufficient flowrate delivery.
Solution Approach 2:
The system changes the pressure parameter dynamically by adjusting the relief valve opening degree according to varying pressure demands of hydraulic devices. Instead of maintaining a fixed design pressure, the system adapts the pressure level in real-time based on actual device requirements, thereby reducing pumping losses when full design pressure is not needed while ensuring adequate pressure delivery when devices require it.
2Productivity
If a main pressure relief valve is proactively controlled in anticipation of a shift event, then shifting performance may be improved, but the system experiences pumping losses when pressure demands are overpredicted, or shifting performance suffers when pressure demands are underpredicted
Solution Approach 1:
The controller receives real-time pressure demand signals from multiple hydraulic devices and uses this feedback to adjust the relief valve opening degree. This closed-loop feedback mechanism allows the system to accurately respond to actual pressure demands without overprediction or underprediction, optimizing both shifting performance and energy efficiency by matching supply pressure precisely to device requirements.
Solution Approach 2:
The relief valve control system serves multiple hydraulic devices simultaneously (clutches, hydrostatic pump, etc.) with a single unified control mechanism. The controller aggregates pressure demands from various devices and coordinates the relief valve to satisfy all devices' requirements, making the system universally applicable to different hydraulic components while avoiding the need for device-specific prediction algorithms that could lead to over or underprediction.
3Device complexity
If the relief valve is not actively controlled, then the system structure is simpler, but pumping losses increase due to circulation of pressurized oil back to tank
Solution Approach 1:
The system replaces a purely mechanical relief valve with an electronically controlled relief valve that receives electrical control signals from the controller. This substitution allows active control of the relief valve opening degree based on real-time pressure demands, enabling the system to minimize pumping losses through intelligent control while maintaining relatively simple hardware architecture by using electronic actuation rather than complex mechanical linkages.
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 effectively reduces pumping losses and increases transmission efficiency by dynamically adjusting the boost pressure to match real-time hydraulic demands, while also decreasing torque absorption during engine cranking.
Implementation Method 1
a relief valve in fluidic communication with the boost pump and a reservoir... actively adjust a position of the relief valve based on an aggregate hydraulic pressure demand of the hydraulic devices to alter a boost pressure
Data Source
AI summary
Methods and systems for a transmission are provided herein. In one example, a hydraulic system is provided that includes a boost pump, a relief valve in fluidic communication with the boost pump and a reservoir, and a plurality of control valves in fluidic communication with the boost pump, positioned downstream of the relief valve, and in fluidic communication with a plurality of hydraulic devices. The hydraulic system further includes a controller designed to actively adjust a position of the relief valve based on an aggregate hydraulic pressure demand of the plurality of hydraulic devices to alter a boost pressure of a hydraulic fluid supplied to the plurality of control valves.