Parking Lock Engagement via Regenerative Braking
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Solution Overview
Problem
Conventional methods for engaging a parking lock in motor vehicle drive trains often result in uncomfortable jerks and high mechanical loads due to abrupt engagement, especially at low speeds, and fail to effectively manage engagement at higher speeds where the parking lock pawl is rejected.
Innovation Solution
A method that detects a parking lock command and uses the electric machine to brake the vehicle when moving, increasing recuperation torque to slow the vehicle below a second threshold, allowing the parking lock actuator to engage the lock at a very low speed, thereby reducing mechanical stress and improving comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the parking lock is engaged while the vehicle is moving at low speed, then the parking lock can be engaged, but the vehicle experiences unpleasant jolts and high mechanical load
Solution Approach 1:
The braking device is activated before the parking lock engagement to reduce vehicle speed to a predetermined threshold. This preliminary deceleration ensures that when the parking lock engages, the mechanical load and jolts are minimized, resolving the contradiction between reliable engagement and harmful mechanical effects.
Solution Approach 2:
The braking device applies a counteracting force to oppose the vehicle's motion before parking lock engagement. This preliminary anti-action reduces the kinetic energy that would otherwise cause harmful jolts and mechanical load during the engagement process.
2Speed
If the parking lock is engaged at higher speeds, then the vehicle speed is higher, but the parking lock pawl is deflected by external contours and cannot engage
Solution Approach 1:
The system detects when vehicle speed exceeds the predetermined threshold and activates the braking device before parking lock engagement is attempted. This preliminary speed reduction ensures the vehicle is decelerated to an appropriate speed range, allowing the parking lock pawl to engage the gear teeth properly without being deflected by external contours.
Solution Approach 2:
The control device continuously monitors vehicle speed and uses this feedback to determine when to activate the braking device. When speed exceeds the threshold, the feedback loop triggers brake activation, which continues until speed is reduced to the predetermined level, ensuring reliable parking lock engagement.
3Object-affected harmful factors
If conventional braking is used to decelerate the vehicle before parking lock engagement, then the vehicle can be slowed down, but the braking distance and time are increased
Solution Approach 1:
The deceleration process is segmented into two phases: first, the electric machine provides regenerative braking to reduce speed, and second, the conventional braking device completes the deceleration to the threshold speed. This segmentation allows efficient use of the electric machine's braking capability while minimizing total braking distance and time.
Solution Approach 2:
The electric machine is used to replace or supplement the conventional mechanical braking system for initial deceleration. By using the electric machine's electromagnetic braking capability, the system achieves faster and more efficient speed reduction compared to conventional braking alone, reducing both braking distance and time.
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 method enhances the engagement quality and comfort of the parking lock, reduces noise, and ensures faster and smoother stopping by initiating braking through the electric machine, thus minimizing mechanical loads on the drive train components.
Implementation Method 1
decelerating the motor vehicle by means of the electric machine when the speed of the motor vehicle is less than a first threshold
Implementation Method 2
a parking lock pawl that, when engaged, engages in tooth gaps on the parking lock wheel to achieve a mechanically positive locking of the vehicle
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The method involves connecting an electric machine (12) with an input or an output of a gear box (14). A parking lock (20) is insertable by a parking lock actuator (22). A parking lock command to the inlaid of parking lock is detected. The velocity of a motor vehicle (11) is detected. The deceleration of the vehicle is performed by the machine, if the velocity of the vehicle is larger than preset threshold level. The actuator is actuated to insert parking lock, if the velocity of the vehicle is smaller than specific threshold level which is smaller than the preset threshold level.