Hydraulic Line Pressure Drop for Progressive Torque Pickup
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Solution Overview
Problem
Existing automatic transmission gearboxes face challenges in regulating progressive torque pickup, particularly in existing designs where the torque take-up curve is not flexible, leading to discomfort for vehicle passengers due to torque surges during gear changes.
Innovation Solution
A hydraulic system with an electronic control unit that temporarily drops line pressure during the closing operation of a hydraulic receiver, using a pressure accumulator to distribute fluid and slow the rise in pressure, allowing for real-time regulation of torque pickup without major material modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high calibration nozzle is used for rapid filling of the receiver, then the filling speed is improved, but the torque surge increases causing passenger discomfort
Solution Approach 1:
The filling process is divided into two distinct phases using two different nozzles: a high calibration nozzle for rapid initial filling and a low calibration nozzle for controlled final filling. This segmentation allows the system to achieve both fast response and smooth torque transfer, eliminating the torque surge that would result from using a single high-calibration nozzle throughout the entire filling process.
Solution Approach 2:
Different parts of the filling process are assigned different nozzle calibration qualities. The high calibration nozzle provides rapid flow capability for the initial phase, while the low calibration nozzle provides flow restriction for the final phase. This local differentiation of flow characteristics allows optimal performance at each stage of receiver pressurization.
2Stress or pressure
If mechanical valves with different nozzle calibrations are used to regulate pressure rise, then the pressure control is improved, but the device complexity increases
Solution Approach 1:
The hydraulic system is designed to use a single existing hydraulic network that supplies all receivers with the same line pressure. By adding only one selective valve that can route pressure through either the high or low calibration nozzle, the system achieves multi-functional pressure control capability without requiring separate hydraulic networks or complex control mechanisms for each receiver.
Solution Approach 2:
A selective valve is introduced as an intermediary component between the hydraulic network and the receiver. This valve acts as a mediator that can direct the hydraulic flow through different paths (high calibration nozzle or low calibration nozzle) based on the system state, providing flexible pressure control without requiring complex modifications to the existing hydraulic architecture.
3Object-affected harmful factors
If the torque take-up curve is made more flexible through valve calibration adjustments, then the comfort is improved, but the adaptability to existing gearboxes is reduced
Solution Approach 1:
The system uses the existing hydraulic network that already serves all receivers with the same line pressure. By leveraging this existing infrastructure and adding only a selective valve with two nozzle options, the system achieves flexible torque take-up control without requiring extensive modifications to the gearbox design, thereby maintaining adaptability to existing gearboxes while improving comfort.
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
This solution enables a more progressive torque pickup, reducing the likelihood of torque surges and enhancing the comfort of gear changes by modulating the line pressure based on variables like turbine speed and oil temperature, thus improving the overall gear change experience.
Implementation Method 1
The first receiver is powered by a first sequence valve and includes a pressure accumulator connected downstream of the first sequence valve parallel to the first receiver. The control unit is configured to trigger filling of the accumulator during the closing operation of the first receiver, so as to distribute the fluid coming from the first sequence valve between the pressure accumulator and the first receiver, and to slow the rise in pressure of the first receiver.
Implementation Method 2
hydraulic receivers of the clutch and/or brake type, supplied at the same line pressure by the same hydraulic network
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a hydraulic system (1), in particular for an automatic transmission of a motor vehicle, which comprises hydraulic actuators (E1, E2, F1, F2, F3), such as clutch and/or brake actuators, supplied at the same line pressure (Pligne) by a single hydraulic circuit (2). The system comprises an electronic control unit (13) configured such as to cause a temporary drop in the line pressure (Pligne) during the closing operation (t0-t8) of one of the actuators (E2) during a change of status in the system, particularly during a gear ratio change from a first ratio to a second ratio.