Transmission Hydraulic Pressure Valve Feedback Against Pump Toggling
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Solution Overview
Problem
Hydraulic systems in automatic transmissions experience oscillations in secondary pump pressure, leading to unsteady conditions and reduced ride comfort due to high pressure and low pressure toggling, which affects the ability of engaged clutches to transmit torque.
Innovation Solution
A hydraulic system design where the secondary output pressure of the pump system is applied to a system pressure valve, using differently sized pistons or a hydraulic pressure splitter circuit to stabilize the system by adjusting the axial load based on pressure conditions, thereby reducing oscillations and enhancing system stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the secondary pump pressure is reduced to lower level, then power consumption and wear are reduced, but the system becomes susceptible to pressure oscillations and toggling
Solution Approach 1:
The patent applies feedback by feeding back a portion of the secondary pump pressure to the system pressure valve. This creates a control mechanism where the pressure state is continuously monitored and adjusted, preventing oscillations while maintaining energy efficiency. The feedback loop allows the system to stabilize at lower pressure levels without experiencing toggling behavior.
Solution Approach 2:
The patent changes the pressure parameter by reducing the secondary pump pressure to a lower level (including approximately zero bar) while using the system pressure valve to regulate and stabilize the pressure. This parameter change enables reduced power consumption while maintaining system stability through active pressure control.
2Stability of the object's composition
If the system pressure valve is attenuated to reduce oscillations, then system stability improves, but the dynamics and response speed of the valve deteriorate
Solution Approach 1:
The patent applies local quality by differentiating the function of different parts of the pressure control system. The system pressure valve maintains good dynamics for rapid response, while the feedback mechanism provides stabilization. This localized functional differentiation allows both fast response and oscillation reduction without compromising overall system performance.
Solution Approach 2:
The patent introduces an intermediary feedback mechanism that mediates between the pressure source and the system pressure valve. This intermediary control path allows the valve to respond quickly to demand changes while the feedback loop gently dampens oscillations, preserving both speed and stability.
3Quantity of substance
If the secondary pump pressure is increased to primary pressure during gear shifts, then volumetric flow rate availability improves, but pressure oscillations and toggling occur
Solution Approach 1:
The patent applies dynamics by making the pressure level adaptive rather than fixed. The secondary pump pressure dynamically adjusts between lower level (for energy efficiency) and primary pressure (for high flow demand), with the feedback mechanism ensuring smooth transitions without oscillations. This dynamic pressure control allows the system to meet varying flow demands while maintaining stability.
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 stabilization of the hydraulic system reduces susceptibility to toggling, ensuring consistent pressure distribution and improved ride comfort by maintaining clutch torque transmission.
Implementation Method 1
A secondary pump pressure acting upon a radial pressure surface of the system pressure valve slide is fed back in a self-regulating manner
Implementation Method 2
The hydraulic system has a pump system with a first pressure outlet and a second pressure outlet, where secondary pump pressure output from the second pressure outlet acts upon the radial pressure surface
Data Source
AI summary
A hydraulic system (1) for a transmission (2) of a motor vehicle (3) includes a pump system (5) with a first pressure outlet (6) and a second pressure outlet (7), a primary circuit (11), a secondary circuit (12), and a system pressure valve (8) that has a system pressure valve slide (9). A secondary pump pressure (PPsek) output from the second pressure outlet (7) of the pump system (5) is fed to a radial pressure surface (26) of the system pressure valve slide (9), and therefore an axial load based on the secondary pump pressure (PPsek) acts upon the radial pressure surface (26) of the system pressure valve slide (9) such that the system pressure valve slide (9) tends to move counter to a mechanical preload force out of a first switching position into a second switching position.