Parking Lock Control Plate Positioning Under Tolerance and Inertia
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Solution Overview
Problem
Existing methods for determining the position of a moving element in a vehicle transmission device, such as a parking lock, are inaccurate due to actuator mounting tolerances and the neglect of rolling element inertia, leading to potential errors in engagement and disengagement of the locking pin.
Innovation Solution
A method that combines angular position sensing with electric motor current measurement to determine the position of a control plate, using a cam profile with concave and convex portions, and adjusts the motor's speed and current to ensure precise positioning by limiting inertia and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only angular position sensor is used to determine the position of the control plate, then the device complexity is reduced, but the measurement precision deteriorates due to actuator mounting tolerances and inertia effects
Solution Approach 1:
The patent combines multiple measurement approaches (angular position sensor readings with electric motor current measurements) to determine control plate position. This merging of measurement methods compensates for the limitations of using only one sensor, achieving higher precision without adding physical sensors to the control plate itself.
Solution Approach 2:
The system uses feedback from electric motor current measurements to compensate for positioning errors. By monitoring the current required to move the control plate and comparing it with expected values, the system can detect and correct for inertia effects and mounting tolerances, improving measurement precision through software-based feedback.
2Ease of operation
If the rolling element is allowed to move freely along the cam track, then the ease of operation is improved, but the manufacturing precision deteriorates due to inertia causing the rolling element to extend beyond the bottom of the concave section
Solution Approach 1:
The patent applies preliminary anti-action by using current-limited motor control to prevent the rolling element from overshooting the desired position due to inertia. The motor current is controlled to counteract the inertial forces that would otherwise cause the rolling element to extend beyond the bottom of the concave section, ensuring precise positioning while maintaining ease of operation.
Solution Approach 2:
The system changes the operational parameters of the electric motor (current limits, speed control) during the positioning process. By adjusting these parameters dynamically, the system can control the rolling element's movement to achieve precise positioning without requiring mechanical constraints that would reduce ease of operation.
3Measurement precision
If additional sensors or components are added to improve position determination accuracy, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent uses electric motor current measurements as an intermediary to indirectly determine control plate position. Instead of adding direct position sensors to the control plate, the system uses the motor's current consumption as a mediator that provides information about the control plate's position and movement state, achieving high precision without increasing device complexity.
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
Achieves a precision target of ±1.5° without additional components, eliminating the need for position learning on assembly lines and adapting to sensor displacement or actuator changes, ensuring accurate engagement and disengagement of the parking lock.
Implementation Method 1
an actuator for driving the moving element between the first and second positions comprising an electric motor
Implementation Method 2
not taking into account the inertia of the rolling element as it travels along the cam track of the control plate, particularly during the downward phases
Implementation Method 3
an angular position sensor for the torque output element that reflects the engaged or disengaged position of the locking pin
Implementation Method 4
By also using the electric motor current measurement, it is possible to obtain an indicator of the torque applied by the actuator to the control plate
Data Source
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AI summary
The present invention relates to a method for controlling the position of a moving element in a vehicle transmission device (1). Said method comprises the following steps: (i) angularly moving a control plate (10), (ii) measuring the angular position of a torque output element of an actuator and comparing the measured value with a limiting threshold value (m), (iii) reducing the rotational speed of the actuator's electric motor, (iv) applying a limited current (Ilim) to the actuator's electric motor, (v) stopping the control of the electric motor when cumulatively the value of the limited current (Ilim) is substantially reached, the measured value of the angular position of the actuator's torque output element corresponds substantially to the desired position, and the angular speed of the torque output element is substantially zero.