Variable Displacement Pump Control for Transmission Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hydraulic pumps in transmissions produce excess fluid flow that leads to hydraulic spin-loss, reducing transmission productivity and performance, and existing solutions fail to efficiently control pump capacity to minimize excess flow and improve shift quality.
Innovation Solution
A hydraulic system with a variable displacement pump controlled by a controller, solenoids, and pressure switches that adjust pump displacement based on fluid pressure and temperature to regulate fluid flow and temperature, using a model-based approach to predict and compensate for system leakage.
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 excess flow and hydraulic spin-loss
Solution Approach 1:
The patent applies a variable displacement pump that dynamically adjusts its fluid flow output based on real-time transmission operating conditions. The pump controller receives signals from pressure switches monitoring main circuit and lube circuit pressures, and from temperature sensors, to continuously vary pump displacement. This dynamic adjustment ensures the pump produces only the necessary fluid flow to meet hydraulic demands, eliminating excess flow and associated spin-loss while maintaining reliable pressure provision across all operating conditions.
2Loss of energy
If a variable displacement pump is used to control pump displacement and reduce excess flow, then fluid flow can be optimized under steady-state conditions, but there is an inherit response time drawback where the demand to increase fluid flow begins before the volume of the pump cavity increases, resulting in undesirable time delay
Solution Approach 1:
The patent implements a controller that proactively manages pump displacement based on predicted hydraulic demands. By monitoring transmission operating state and using pressure switch feedback, the controller anticipates upcoming flow requirements (such as clutch fill demands during shifts) and adjusts pump displacement in advance. This preliminary action ensures fluid flow is increased before the actual demand occurs, eliminating the time delay inherent in reactive variable displacement systems while still maintaining excess flow reduction during steady-state operation.
3Productivity
If pump capacity is electronically controlled to minimize excess flow, then transmission efficiency and fuel economy are improved, but the system complexity increases with additional controllers, solenoids, and sensors
Solution Approach 1:
The patent integrates the pump controller functionality within the existing transmission control architecture, allowing the same controller to manage multiple functions including pump displacement control, shift timing, and other transmission operations. Pressure switches and temperature sensors serve dual purposes by monitoring both pump operation and overall transmission health. This multi-functionality approach enables electronic pump capacity control and the associated productivity improvements without proportionally increasing system complexity, as control elements serve multiple purposes within the transmission system.
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 minimizes excess fluid flow, improves shift quality, reduces spin losses, and enhances transmission efficiency and fuel economy by accurately controlling fluid flow and temperature.
Implementation Method 1
The pump is adapted to be driven by a torque-generating mechanism and is configured to generate fluid flow and pressure throughout the system
Implementation Method 2
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
Implementation Method 3
A pressure switch is fluidly coupled to the main regulator valve and is configured to move between a first position and a second position
Implementation Method 4
The main regulator valve is configured to move between at least a regulated position and an unregulated position, where the regulated position corresponds to a regulated pressure in the main circuit
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A hydraulic system of an automatic transmission, comprising a controller for operably controlling the system, a variable displacement pump (202) adapted to be driven by a torque-generating mechanism, the pump having an inlet and an outlet, where the pump is configured to generate fluid flow and pressure throughout the system, and a solenoid disposed in electrical communication with the controller, the solenoid controllably coupled to the pump to alter the displacement of the pump. A first fluid circuit is fluidly coupled to the outlet of the pump, the first circuit adapted to operate and control the transmission, a regulator valve (204) is disposed in fluid communication with the main circuit, the regulator valve being configured to move between a regulated position and an unregulated position, where the regulated position corresponds to a regulated pressure in the main circuit. A second circuit is fluidly coupled to the pump, the second circuit operably controlled to adjust a temperature of the fluid in the system. A temperature sensor is disposed in electrical communication with the controller, the temperature sensor adapted to detect the temperature of the fluid, and a plurality of flow paths are provided in the system, the plurality of flow paths comprising at least a first flow defined between the outlet of the pump and the regulator valve, a second flow path defined between the regulator valve and the main circuit, and a third flow path defined between the regulator valve and the second circuit.