Direct Clutch Slip Control via Closed-Loop Speed Feedback
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Solution Overview
Problem
Existing automatic transmission control systems face challenges in precisely controlling clutches due to variations in environmental conditions and transmission wear over time, leading to inefficiencies and potential damage, as they often rely on open loop control methods that require calibration and are less precise.
Innovation Solution
Implementing a closed loop control system that uses rotational speed sensors to directly measure and respond to clutch engagement and disengagement, allowing for precise control of gear ratios without needing to account for environmental conditions or transmission wear, by adjusting control signals based on real-time feedback from sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open loop control methods are used for clutch engagement, then the control system is simpler to implement, but the control precision deteriorates due to variations in environmental conditions and transmission wear
Solution Approach 1:
The patent implements a closed-loop control system that uses rotational speed sensors to continuously monitor the actual rotational speeds of the input and output shafts. The control system compares these measured speeds with the desired speeds and dynamically adjusts the clutch engagement control signals in real-time to eliminate any speed differential errors, thereby maintaining high precision despite environmental variations and component wear.
2Measurement precision
If calibration is performed to account for environmental conditions and wear, then control accuracy may be improved, but the time and resources required for calibration increase
Solution Approach 1:
The control system performs self-calibration by continuously monitoring the actual rotational speeds during normal operation and automatically adjusting the control parameters. The system uses the measured speed differentials during clutch engagement to dynamically update control profiles, eliminating the need for separate calibration procedures and allowing the system to adapt to wear and environmental changes autonomously over time.
3Measurement precision
If rotational speed sensors and closed loop control are implemented, then clutch engagement precision is improved, but the device complexity increases
Solution Approach 1:
The patent introduces rotational speed sensors as intermediary measurement devices that bridge the gap between the clutch engagement control system and the actual mechanical state. These sensors provide real-time feedback on the rotational speeds of the input and output shafts, enabling the control system to make precise adjustments without requiring direct measurement of clutch engagement forces or pressures, thereby simplifying the overall measurement approach while maintaining high precision.
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 approach enhances the precision and efficiency of clutch engagement and disengagement, reducing energy losses, improving fuel efficiency, and providing a smoother ride by directly monitoring and adjusting clutch operations, thus reducing the need for costly calibration and component precision.
Implementation Method 1
a plurality of rotational speed sensors. Each rotational speed sensor is operable to measure rotational speeds relative to the transmission housing for of one of the input shaft, the output shaft, or one of the plurality of gears
Implementation Method 2
the clutches are hydraulically controlled. In some examples, the components of a hydraulically controlled clutch include an electric solenoid driver, a clutch solenoid and the clutch itself. In order to control a clutch, the electric solenoid driver delivers an electrical signal to activate the clutch solenoid, which, in turn, controls hydraulic fluid pressure in order to control the clutch
Implementation Method 3
the electric solenoid driver delivers an electrical signal to activate the clutch solenoid, which, in turn, controls hydraulic fluid pressure
Data Source
AI summary
An automatic transmission for a vehicle drivetrain includes a transmission housing, an input shaft, an output shaft, and a plurality of gears within the transmission housing. The plurality of gears defines multiple mechanical gear ratios between the input shaft and the output shaft. The transmission further includes a plurality of clutches operable to selectively engage the multiple mechanical gear ratios, and a plurality of rotational speed sensors. Each rotational speed sensor is operable to measure rotational speeds relative to the transmission housing for of one of the input shaft, the output shaft, or one of the plurality of gears. The transmission further includes a transmission control system configured to receive signals representing the measured rotational speeds from the plurality of rotational speed sensors and control the plurality of clutches to change between gear ratios based at least in part on the signals representing the measured rotational speeds.