Automated Drive Train Clutch Damping for Parking Lock Noise
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Solution Overview
Problem
Automated powertrains experience loud and undesirable noise when the parking lock mechanism is disengaged on a slope due to torque from downhill forces, leading to concerns about transmission damage.
Innovation Solution
The method involves engaging a gear and introducing counter-torque via a clutch to dampen the relaxation movement of the drive train, using a slipping clutch to reduce tension and noise, and employing transmission control to detect vehicle inclination and adjust the clutch torque accordingly, ensuring the clutch remains below the slip condition to prevent speed fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the parking lock mechanism is disengaged on a slope without applying the parking brake, then the vehicle can be moved from the parked position, but loud switching noises occur due to the relaxation movement of the twisted output train
Solution Approach 1:
The parking brake is applied before disengaging the parking lock mechanism. This preliminary action prevents the output train from being twisted by downhill forces during the disengagement process, thereby eliminating the relaxation movement that causes loud switching noises.
Solution Approach 2:
The parking brake serves as a cushioning mechanism that absorbs the downhill forces before the parking lock is disengaged. By applying the parking brake in advance, the system prevents the buildup of torque in the output train, thus cushioning against the harmful relaxation movement and associated noise.
2Reliability
If the parking lock mechanism is engaged to secure the vehicle on a slope, then the vehicle remains stationary, but the output train becomes twisted and stores potential energy
Solution Approach 1:
The parking brake acts as an intermediary element that shares the load of holding the vehicle on a slope. Instead of the parking lock mechanism alone bearing the full downhill force, the parking brake intervenes to support part of the load, thereby reducing the tension and potential energy storage in the output train while maintaining vehicle stability.
3Object-generated harmful factors
If the clutch is actuated to introduce counter-torque into the drive train, then the relaxation movement is damped and noise is reduced, but the clutch operates in a slip condition causing speed fluctuations
Solution Approach 1:
The clutch slip condition, which normally causes speed fluctuations and is considered harmful, is utilized beneficially to introduce counter-torque into the drive train. This counter-torque dampens the relaxation movement of the output train, converting the potential harm of clutch slip into the benefit of noise reduction during parking lock disengagement.
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 approach significantly reduces the noise associated with parking lock disengagement, allowing for smooth operation and eliminating the perception of transmission damage, regardless of the vehicle's parking position.
Implementation Method 1
The slipping clutch itself makes a significant contribution to noise reduction, in that the tension in the drive train can be reduced over a longer period of time
Implementation Method 2
a single-acting cylinder also located inside the transmission housing, which advances the actuating rod in the pressureless state, i.e. keeps the parking lock closed via a spring
Data Source
Figure 1
Figure 2
AI summary
The method involves connecting a transmission input shaft (3.2) with an engine (36) of a motor vehicle (1) by a transmission-input side clutch (2.1). A transmission output shaft (12) is connected to drive wheels of the vehicle. A positive connection is provided between the drive train and a fixed portion e.g. transmission casing, of the vehicle by a parking lock mechanism (32). A gear stage is inserted before and/or during deactivation process of the mechanism so that relaxation movement developed during the process is absorbed or controlled by drag moments at the clutch.