Vehicle Parking Lock Tension Management via Service Brake Control
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Solution Overview
Problem
The existing systems for actuating braking devices in vehicles with automatic transmissions face challenges in preventing disengagement impacts when releasing the parking lock, particularly on inclines, due to the buildup of tension which can lead to unpleasant jolts and increased effort required for disengagement.
Innovation Solution
A method and control device that secure the vehicle against rolling away using the service brake before releasing the parking lock, ensuring the parking lock can be disengaged without significant tension by maintaining or adjusting brake pressure independently of the driver's input, thereby preventing disengagement impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the parking lock is engaged on an incline to secure the vehicle, then the vehicle is secured against rolling away, but tension builds up in the parking lock mechanism causing disengagement impacts and increased effort for disengagement
Solution Approach 1:
The control device activates the service brake before disengaging the parking lock to pre-establish a braking force that will secure the vehicle against rolling away. This preliminary action ensures that when the parking lock is disengaged, the service brake is already applied and will prevent any rolling movement, thereby avoiding tension release impacts and reducing disengagement effort.
Solution Approach 2:
The service brake acts as an intermediary mechanism between the parking lock and the vehicle's rolling resistance. Instead of relying solely on the parking lock to counteract gravitational force on inclines, the service brake provides additional braking force that shares the load and prevents sudden tension release when the parking lock disengages.
2Reliability
If the parking lock is engaged to prevent vehicle movement, then the vehicle remains stationary, but the parking lock mechanism experiences high tension and potential damage
Solution Approach 1:
The control device applies the service brake in advance before disengaging the parking lock, ensuring that a sufficient braking force is already present to counteract gravitational forces. This preliminary application of the service brake prevents the parking lock mechanism from experiencing high tension during disengagement, thereby protecting it from damage and extending its service life.
Solution Approach 2:
The service brake, which is primarily designed for dynamic braking, is utilized to prevent the harmful effects of high tension on the parking lock mechanism. By converting the service brake's capability into a preventive measure, the system protects the parking lock from damage that would otherwise occur during disengagement on inclines.
3Object-affected harmful factors
If the service brake is activated before parking lock disengagement, then disengagement impacts are prevented, but additional control complexity is introduced
Solution Approach 1:
The control device integrates multiple functions into a single control unit that manages both the service brake and parking lock operations. This universal control device coordinates the activation of the service brake and the disengagement of the parking lock, preventing disengagement impacts while avoiding the need for separate complex control systems.
Solution Approach 2:
The control device automatically manages the coordination between the service brake and parking lock without requiring additional manual intervention from the driver. The system self-regulates by detecting when the parking lock is engaged and automatically applying the service brake before disengagement, thereby preventing impacts without adding operational complexity for the user.
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 solution allows for the reliable prevention of disengagement impacts by ensuring the parking lock can be unloaded without tension, reducing component stress and lowering the effort required for disengagement, while maintaining vehicle security against rolling away.
Implementation Method 1
The service brake mainly enables the vehicle speed to be reduced until the vehicle comes to a standstill
Implementation Method 2
The service brake is often designed as a hydraulic service brake, in which the braking force is transmitted hydraulically by fluid pressure in the brake lines
Data Source
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AI summary
The invention relates to a method for actuating a braking device of a vehicle powertrain having an automatic transmission, comprising a transmission-side parking lock and comprising at least one brake system. According to the invention, when the vehicle is parked and the parking lock is engaged, the vehicle is secured against rolling by at least one brake system until the parking lock is released when a start-up condition is present, preferably regardless of the driver's wish and/or preferably in a controlled manner using at least one controller.