Transmission Pump Displacement Control for Spin-Loss Reduction
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Solution Overview
Problem
Conventional hydraulic pumps in transmissions tend to overproduce fluid flow at higher engine speeds, leading to excess fluid flow that contributes to hydraulic spin-loss, reducing transmission productivity and performance, and introducing time delays in clutch filling due to inherent response time drawbacks in variable displacement pumps.
Innovation Solution
A hydraulic system with a variable displacement pump controlled by a controller, solenoid, and pressure switches that adjust pump displacement based on fluid pressure and temperature, minimizing excess flow and optimizing fluid flow distribution to improve shift quality and reduce spin losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional hydraulic pump is designed to provide adequate fluid flow at low engine idle speed and full regulated pressure at specific engine speed, then the pump can meet transmission hydraulic demands, but the pump overproduces fluid flow at or above normal operating conditions, leading to hydraulic spin-loss
Solution Approach 1:
The patent applies a variable displacement pump that dynamically adjusts its fluid output based on transmission operating conditions. The pump controller receives signals from pressure switches monitoring main circuit and lube circuit pressures, then adjusts pump displacement accordingly. This dynamic adjustment allows the pump to match fluid supply with actual transmission demands across varying engine speeds, eliminating the overproduction of fluid flow that causes hydraulic spin-loss while maintaining adequate flow at idle speeds.
2Loss of energy
If a variable displacement pump is used to control pump displacement and reduce excess flow, then hydraulic spin-loss is reduced, but there is an inherent response time drawback causing time delay to fill the clutch
Solution Approach 1:
The patent employs pressure switches that detect pressure conditions in advance and trigger controller actions before clutch filling demands peak. The main circuit pressure switch and lube circuit pressure switch monitor system pressure and activate pump displacement adjustments proactively, allowing the variable displacement pump to begin increasing flow output before the clutch fill demand fully materializes. This preliminary action reduces the effective response time delay while maintaining the energy efficiency benefits of variable displacement control.
3Quantity of substance
If additional fluid flow is produced by the pump beyond what is needed for control and lube systems, then the transmission can meet hydraulic demands, but the excess fluid flow is returned to transmission sump and contributes to hydraulic spin-loss
Solution Approach 1:
The patent implements a feedback control system where pressure switches continuously monitor main circuit and lube circuit pressures and relay information to the pump controller. The controller adjusts pump displacement based on this feedback, increasing flow only when transmission hydraulic demands require it and reducing flow when demands are met. This feedback mechanism ensures fluid quantity matches actual transmission productivity needs, preventing excess fluid from being returned to the sump and eliminating the associated hydraulic spin-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 effectively controls fluid flow and pressure to minimize excess flow, enhance transmission productivity, and improve shift quality by adjusting pump displacement in real-time, reducing spin losses and fuel consumption.
Implementation Method 1
A solenoid is disposed in electrical communication with the controller, such that the solenoid is controllably coupled to the pump to alter the displacement of the pump
Data Source
AI summary
A hydraulic system of a transmission having a controller and a variable displacement pump. The pump includes an inlet and outlet and is adapted to be driven by a torque-generating mechanism. The system also includes a lube circuit fluidly coupled to the pump. A lube regulator valve is disposed in the lube circuit, such that the lube regulator valve is configured to move between at least a regulated position and an unregulated position. The regulated position corresponds to a regulated pressure in the lube circuit. A pressure switch is fluidly coupled to the lube regulator valve and configured to move between a first position and a second position, where the switch is disposed in electrical communication with the controller. A solenoid is disposed in electrical communication with the controller and is controllably coupled to the pump to alter the displacement of the pump.