EV Parking Lock Gear Positioning for Smooth Pawl Engagement
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Solution Overview
Problem
Electrically driven vehicles face issues with parking locks engaging abruptly when parked on slopes, causing mechanical stress and discomfort due to the pawl hitting the parking lock gear, leading to vibrations and torque fluctuations.
Innovation Solution
A method involving an actuator to bias a spring, position sensing of the parking lock gear, determination of the rotor shaft's angle of rotation to reach the nearest tooth space, and controlled rotation by the electric motor to gently roll the vehicle into the parking lock without additional sensors or brake pressure, using existing components like resolvers and translational movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the driver releases the brakes after parking on a slope, then the vehicle starts to roll and the pawl engages in the next gap of the parking lock gear, but this causes the vehicle to stop abruptly, resulting in vibrations and torques that put mechanical stress on the drivetrain components
Solution Approach 1:
The control unit determines the angle of rotation of the rotor shaft to reach the nearest tooth space of the parking lock gear before the pawl engagement occurs. By pre-calculating the required rotation angle and controlling the electric motor to achieve this position, the system ensures that the pawl engages smoothly at the predetermined tooth space rather than abruptly hitting a tooth, thereby eliminating mechanical stress and vibrations while maintaining reliable parking lock engagement.
2Object-affected harmful factors
If additional sensors or brake pressure control are used to make the rolling more gentle, then comfort is improved, but device complexity and cost increase
Solution Approach 1:
The system uses existing components already present in electrically driven vehicles - specifically the electric motor and the resolver (position detection system) - to achieve gentle rolling into the parking lock. The control unit utilizes the rotor shaft's angle of rotation information from the resolver to calculate the precise rotation needed for smooth pawl engagement. This self-service approach eliminates the need for additional sensors or complex brake pressure control systems, reducing device complexity and cost while improving comfort and reducing mechanical stress.
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
Enables gentle rolling of the vehicle into the parking lock without additional hardware, reducing mechanical stress and improving comfort by using existing components for position detection and controlled motor operation, applicable to both new and retrofitted vehicles.
Implementation Method 1
Control of the electric motor for sweeping the angle of rotation determined in accordance with c) and a controlled approach to the position of the tooth space determined in accordance with c)
Implementation Method 2
biasing of a biasing spring by an actuator when the parking lock device is activated
Data Source
AI summary
The invention relates to a method for rolling an electrically driven vehicle (10) into a parking lock device (44) from a position in which a pawl (48) is prevented from locking a parking lock gear (46). When the parking lock device (44) is activated, a biasing spring (54) is biased by an actuator (52). A position, identified by position sensing (36), of a parking lock gear (46) accommodated in a rotationally fixed manner is then sent to a control unit (40). Subsequently, an angle of rotation of the rotor shaft (34) of an electric motor (14) which is required to reach the nearest tooth space (60) of an outer toothing (56) of the parking lock gear (46) is determined. The electric motor (14) is then activated in order for the determined angle of rotation to be swept and a controlled approach to be made to the position of the determined closest tooth space (60). The invention further relates to the use of the method for rolling an electrically driven vehicle (10) into a parking lock device (44) from a position in which a pawl (48) is prevented from locking a parking lock gear (46).