Adaptive Transmission Pump Control for Excess Flow and Shift Delay
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Solution Overview
Problem
Conventional hydraulic pump systems in transmissions tend to overproduce fluid flow at higher engine speeds, leading to excess flow that contributes to hydraulic spin-loss and reduces transmission productivity and performance, with existing solutions like variable displacement pumps experiencing delays in responding to fluid demand, affecting fuel economy and shift quality.
Innovation Solution
A method of electronically controlling pump capacity through a feed forward model that uses pressure switches and a pump control solenoid to adjust pump displacement, anticipating fluid demands and minimizing excess flow by learning the leakage adaptive constants of the hydraulic system, thereby improving shift quality and reducing 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 under various operating conditions, but the pump tends to overproduce fluid flow at or above normal operating conditions and engine speeds
Solution Approach 1:
The patent applies dynamics by making the pump displacement variable rather than fixed. The pump controller dynamically adjusts the pump displacement based on real-time hydraulic demand signals from pressure switches, allowing the pump to adapt its fluid flow output to match actual transmission needs across different engine speeds and operating conditions, thereby eliminating excess flow and hydraulic spin-loss.
Solution Approach 2:
The patent changes the parameter of pump displacement from a fixed design value to a dynamically adjustable parameter. By modifying the displacement parameter in response to hydraulic demand signals, the pump can optimize its fluid flow production to match actual system requirements, preventing overproduction and associated energy losses.
2Loss of energy
If a variable displacement pump is used to control pump displacement and reduce excess flow, then the pump can produce a more desirable amount of flow under steady-state conditions, but there is an inherit response time drawback when the transmission is in certain ranges
Solution Approach 1:
The patent applies preliminary action by having pressure switches continuously monitor hydraulic circuit conditions and send demand signals to the pump controller in advance. This early detection and signaling system allows the pump controller to anticipate and prepare for upcoming hydraulic demands, reducing the response time delay when the transmission needs additional fluid flow.
3Stress or pressure
If the pump is designed to provide full regulated pressure to the main pressure circuit at a specific engine speed, then the transmission receives adequate pressure for clutch filling and operation, but additional fluid flow produced by the pump is generally returned to transmission sump and is unusable
Solution Approach 1:
The patent applies feedback by using pressure switches in the hydraulic circuits to continuously monitor pressure conditions and send signals back to the pump controller. This feedback mechanism allows the pump controller to adjust pump displacement in real-time based on actual hydraulic demand, ensuring that fluid flow is produced only when and where needed, thereby eliminating unusable excess flow that would otherwise be returned to the transmission sump.
Data Source
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AI summary
The present disclosure provides 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.