Automatic Transmission Parking Lock Actuation Control
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Solution Overview
Problem
Existing automatic and automated motor vehicle transmissions face challenges in maintaining high drivability and maneuverability while automatically engaging the parking lock, often resulting in unintended immobilization, especially when the driver is not attentive or in specific operating conditions.
Innovation Solution
A method that allows for a separate operating device to activate a holding phase, placing the transmission in a traction-free neutral position independently of the gear selection, based on conditions like vehicle stillness, ignition interruption, and gear position, ensuring the vehicle can coast without automatic parking lock engagement, and includes additional criteria for activation and deactivation to prevent unintentional immobilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the parking lock is automatically engaged when ignition is interrupted and vehicle speed is low, then vehicle security is improved, but vehicle availability and maneuverability deteriorate due to unintended immobilization
Solution Approach 1:
The system dynamically adjusts the engagement behavior of the parking lock based on real-time operating conditions. Instead of a static automatic engagement rule, the control device evaluates multiple parameters (ignition state, vehicle speed, gear position, brake status) to dynamically determine whether automatic engagement should occur, thereby adapting security measures to actual operational context
Solution Approach 2:
The invention changes the parameters governing parking lock engagement from a simple speed-threshold rule to a multi-parameter decision matrix. The control device considers ignition circuit state, vehicle speed, selected gear position, and brake application status simultaneously to determine engagement behavior, transforming a single-parameter control system into a multi-parameter adaptive system
2Use of energy by moving object
If the transmission automatically shifts to neutral when drive motor is not operating, then energy consumption is reduced, but drivability deteriorates due to loss of manual control
Solution Approach 1:
The system prepares the transmission for potential neutral shifting by monitoring operating conditions in advance, but only executes the shift when specific criteria are met. The control device continuously evaluates whether the drive motor is operating and whether automatic neutral engagement conditions are satisfied, performing the action preliminarily rather than immediately, thus maintaining driver intent while enabling energy savings when appropriate
3Reliability
If the parking lock engagement conditions are expanded to include multiple parameters, then false automatic engagement is reduced, but system complexity increases
Solution Approach 1:
The transmission control device performs multiple functions simultaneously: it manages gear shifting, monitors operating parameters, determines engagement conditions, and controls the parking lock actuator. By making the control device universal and multi-functional, the system avoids adding separate dedicated components for each function, thereby managing complexity while achieving reliable multi-parameter evaluation
Data Source
AI summary
A method of actuating a gear step in an automatic or automated transmission of a motor vehicle. The gear step of the transmission and a parking lock, which immobilizes the vehicle, can be engaged as a function of a gear step (P, R, N, D) that can be selected by the driver via a controllable selector device, and as a function of other motor vehicle operating parameters. A separate operating device, which is in addition to the selector device, can activate a holding phase, in which the transmission is in a traction-free neutral position, independently of a predetermined gear step “Park” (P), “Reverse” (R), “Neutral” (N) and/or “Forward” (D) that is specified by the selector device, if the motor vehicle is at least almost at a standstill and at the same time, an ignition circuit acting on a drive motor of the motor vehicle is electrically interrupted.