EV Transmission Clutch Pressure Control for Stable Gear Shifts
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Solution Overview
Problem
Position-based clutch actuators in electric vehicles experience instabilities due to the simplification of gear states required by electric motors, leading to inefficiencies in clutch operation.
Innovation Solution
A method and system that utilize a processor to receive a pressure signal for the clutch, determine the piston position using a transfer function, and calculate corrections based on motor speed parameters, drag, and pressure feedback to stabilize clutch operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a position-based clutch actuator is used to simplify gear states for electric motors, then device complexity is reduced, but stability deteriorates causing motor speed fluctuations
Solution Approach 1:
The patent implements a feedback control system where the actual piston position is measured and compared with the desired position, and the difference (error) is used to adjust the actuator output. This closed-loop feedback mechanism compensates for position inaccuracies and stabilizes motor speed during clutch engagement, resolving the contradiction between simplified actuator design and stability requirements.
Solution Approach 2:
The patent dynamically adjusts control parameters including piston position, fluid pressure, and engagement speed based on real-time operating conditions. By changing these parameters adaptively rather than using fixed position-based control, the system maintains stability while keeping the actuator structure simple, thus resolving the technical contradiction.
2Productivity
If the piston is moved quickly to engage the clutch, then productivity is improved, but stability deteriorates causing speed fluctuations
Solution Approach 1:
The patent employs a two-stage clutch engagement process: first a rapid initial engagement to quickly establish connection, followed by a slower refinement phase where the piston continues moving at reduced speed while feedback control adjusts for any oscillations. This periodic variation in actuation speed allows both high productivity and stability.
Solution Approach 2:
The control system dynamically adjusts the piston movement speed based on real-time feedback about clutch engagement status and motor speed stability. The system transitions from fast movement to slow movement automatically, making the actuation process adaptive rather than static, thus achieving both speed and stability.
3Stability of the object's composition
If pressure-based control is used instead of position-based control, then stability is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical position sensing and control mechanisms with a simpler pressure-based control system. By using fluid pressure as the primary control variable and measuring it with relatively simple pressure sensors, the system achieves stable clutch engagement without requiring complex mechanical position feedback mechanisms, thus improving stability while limiting complexity increase.
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 solution effectively reduces motor speed fluctuations during gear shifts, enhancing the stability and efficiency of clutch engagement and disengagement in electric vehicle transmissions.
Implementation Method 1
A position for a piston of an actuator for the clutch is determined from the pressure signal at the processor
Implementation Method 2
The transfer function determines the position based on the pressure signal and a temperature
Implementation Method 3
The piston is moved to the position to operate the clutch at the selected fluid pressure
Implementation Method 4
calculating at least one of a drag correction based on the position of the piston and a previous position of the piston
Implementation Method 5
a pressure feedback correction based on a difference between a current fluid pressure at the clutch and the pressure signal
Data Source
AI summary
A vehicle includes a transmission that performs a method of operating a clutch of a vehicle. The vehicle includes the clutch, an actuator device and a processor. The actuator device includes a piston movable to operate the clutch. The processor is configured to receive a pressure signal indicative of a selected fluid pressure for operating the clutch, determine a position for the piston in the actuator device from the pressure signal, and move the piston to the position to operate the clutch at the selected fluid pressure.