Variable Displacement Pump Control for Transmission Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current automatic transmissions face issues with large and costly valve body assemblies, hydraulic response time delays, temperature sensitivity, and reduced fuel economy due to inefficient fluid control systems, including indirect variable displacement pump controls and one-way-clutches.
Innovation Solution
A closed-loop electro-hydraulic control system using a variable displacement pump, pressure sensor, and actuating valve to optimize fluid flow, eliminating the need for a large bleed circuit and reducing pump displacement, thereby improving hydraulic efficiency and fuel economy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional valve body assembly with multiple solenoids and regulator valves is used to control clutches and brakes, then the transmission can achieve gear ratios, but the valve body size and cost increase due to many layers
Solution Approach 1:
The patent combines multiple control functions into a single integrated electro-hydraulic control unit that directly controls pump displacement. This merges the functions of multiple solenoids, regulator valves, and latch valves into one compact assembly, reducing the overall valve body size while maintaining gear ratio control capability.
Solution Approach 2:
The patent extracts the pump displacement control function from the conventional valve body assembly and creates a dedicated control unit. This separation allows the main valve body to be smaller while the extracted control unit handles pump displacement independently, resolving the size complexity trade-off.
2Adaptability or versatility
If a conventional valve body assembly with multiple regulator and latch valves is used, then gear control is achieved, but hydraulic response time delays increase due to multiple stages
Solution Approach 1:
The patent extracts the pump displacement control function from the multi-stage valve body assembly and creates a dedicated control unit with direct solenoid-to-pump actuation. This eliminates the multiple regulatory stages (solenoid output → regulator valve input → regulator output) that cause time delays, while maintaining gear control capability.
Solution Approach 2:
The patent segments the control system into independent functional units: a dedicated pump displacement control unit and a gear control unit. This segmentation allows the pump control to respond independently and rapidly without being constrained by the multi-stage valve body timing, reducing overall hydraulic response time.
3Adaptability or versatility
If conventional indirect variable displacement pump control is used, then pump displacement control is achieved, but system stability decreases and fluid flow rate becomes much higher than needed
Solution Approach 1:
The patent implements a closed-loop feedback control system where a flow sensor directly measures pump output flow and feeds this information back to the solenoid control. This direct feedback stabilizes the system by continuously adjusting pump displacement to match actual flow requirements, preventing the instability and excessive flow rates associated with indirect control methods.
4Adaptability or versatility
If conventional indirect variable displacement pump control is used, then pump displacement control is achieved, but fuel economy deteriorates due to excessive fluid flow rate
Solution Approach 1:
The patent uses direct flow sensor feedback to precisely control pump displacement according to actual transmission needs. This prevents the excessive fluid flow generation of indirect control systems, reducing hydraulic power losses and improving fuel economy by approximately 0.5% as stated in the patent.
Solution Approach 2:
The patent dynamically changes pump displacement parameters based on real-time flow requirements detected by the sensor. This allows the pump to operate at optimal displacement levels rather than generating excessive flow, directly reducing energy losses and improving fuel economy.
5Stability of the object's composition
If a large bleed circuit is used to stabilize the variable displacement pump, then pump stability is improved, but hydraulic power is lost reducing fuel economy
Solution Approach 1:
The patent replaces the large passive bleed circuit with an active closed-loop feedback control system using a flow sensor. This feedback mechanism stabilizes the pump through precise control rather than through power-dissipating bleed flows, eliminating the trade-off between stability and energy loss.
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 reduces the size of the valve body, shortens gear shift times, and improves fuel economy by approximately 0.5% through optimized fluid delivery and reduced pumping flow, achieving a 25% reduction in pumping flow.
Implementation Method 1
a pressure sensor, the pressure sensor producing a variable control signal whose magnitude represents a degree to which fluid flow requirements of the transmission are being provided by the fluid source
Implementation Method 2
an actuating valve producing a pressure that changes the pump displacement in response to the magnitude of the control pressure
Data Source
AI summary
A system for controlling fluid flow rates in a transmission includes a pump having variable displacement and providing a pressurized fluid source, a regulating valve communicating with the fluid source and a pressure sensor, the pressure sensor producing a variable control signal whose magnitude represents a degree to which fluid flow requirements of the transmission are being provided by the fluid source, and an actuating valve producing a pressure that changes the pump displacement in response to the magnitude of the control pressure.