Power Window Anti-Pinch Control Using Back-EMF Position Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power-window systems in vehicles lack precise and sensorless methods for determining the position of windows during operation, especially in the presence of obstacles, leading to potential pinching issues.
Innovation Solution
A method utilizing the electrical quantities of a DC electric motor, specifically back electromotive force and armature current, to estimate the position of the window without external sensors, enabling continuous control by counting oscillation periods and reversing the motor direction if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external sensors are used to detect window position, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The motor serves itself by providing position information through its own electrical characteristics (back EMF and current oscillations) without requiring external sensors. The control unit extracts position data from the motor's inherent electrical signals, making the system self-sufficient and eliminating the need for separate detection devices
Solution Approach 2:
The patent replaces mechanical/sensor-based position detection with an electrical field-based method. By analyzing the electrical quantities (back EMF and armature current) of the motor, the system achieves position detection without mechanical sensors, thereby reducing hardware complexity while maintaining measurement precision
2Reliability
If anti-pinch function is implemented with high sensitivity, then reliability is improved, but false detection may increase due to system variations
Solution Approach 1:
The control unit continuously monitors the motor's electrical quantities and uses feedback from the oscillation period analysis to determine window position and detect obstacles. This closed-loop feedback mechanism allows the system to adapt to system variations and maintain reliable anti-pinch detection
Solution Approach 2:
The patent changes the detection parameter from direct position measurement to oscillation period counting of electrical quantities. By monitoring changes in the oscillation periods of back EMF and armature current, the system can detect position changes and obstacles reliably while being insensitive to absolute parameter variations
3Measurement precision
If continuous position control is implemented in all motor operating steps, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The motor's electrical quantities naturally provide continuous position information throughout all operating steps including shutdown. The control unit processes these self-generated signals to maintain continuous position awareness without requiring additional control hardware or complex external sensing systems
Solution Approach 2:
The motor serves multiple functions: it provides both the driving force and the position detection signals simultaneously. The same electrical quantities used for motor control also contain position information, eliminating the need for separate detection systems and reducing overall device complexity while achieving continuous position control
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
Enables precise and continuous window position detection without sensors, ensuring reliable anti-pinch functionality across various operating conditions, including motor shutdown, while reducing hardware complexity and cost.
Implementation Method 1
A method utilizes the electrical quantities of a DC electric motor, specifically back electromotive force and armature current, to estimate the position of the window
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An anti-pinch method for an apparatus for automatic movement of sliding windows in a motor vehicle, in particular a power-window apparatus, comprising a d.c. electric motor (M) that moves a window (F) so that it slides along guides, said method comprising: - receiving at least one electrical quantity (ea, ia) of said motor (M); - counting (Rc) oscillation periods (Rd) of said at least one electrical quantity (ea, ia); - calculating an angular position (θ(t) ) of the motor (M) as a function of the number of periods (Rc) of the electrical quantity (ea, ia); - calculating a position of the window (F) as a function of said angular position ( 9(t) ) of the motor (M); and - reversing the direction of rotation of the motor (M) if the position of said window (F) falls within an anti-pinch zone (APZ) and the movement of the motor (M) is at least partially blocked. The method described envisages: - receiving a plurality of electrical quantities (ea, ia) of said motor (M); and - selecting the electrical quantity in order to count (Rc) oscillation periods (Rd) of said at least one electrical quantity (ea, ia) in said plurality of electrical quantities (ea, ia) received through a control signal (mode), generated as a function of the operating steps (STOP, RUN UP, RUN DOWN) of the motor (M).