Parking Lock Actuator With Inductive Position Sensing
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Solution Overview
Problem
Existing actuators for motor vehicle automatic transmissions face challenges in reliably determining their position, especially during power failures or mechanical issues, and require an independent voltage source for emergency mechanisms, which can fail if the vehicle's accumulator is discharged.
Innovation Solution
An actuator with an inductive measuring system using a coil to generate a magnetic field and detect eddy currents in conductive materials, allowing for precise position determination without additional sensors, and an emergency adjustment device for actuating the parking lock even in power failure scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an independent voltage source is used to trigger the emergency mechanism, then the emergency function can be activated, but the system fails when the voltage source is unavailable (e.g., discharged battery)
Solution Approach 1:
The patent extracts the voltage source requirement from the emergency mechanism by using a purely mechanical spring element that is preloaded and held by a latch. This mechanical emergency mechanism can be triggered without any voltage source, eliminating the reliability issue of voltage-dependent emergency systems.
Solution Approach 2:
The spring element serves itself by being preloaded during normal operation and automatically engaging the parking lock when triggered. The mechanical system uses its own stored energy (preloaded spring) rather than requiring external power, making the emergency function self-sufficient.
2Measurement precision
If additional sensors are added to determine actuator position, then measurement accuracy improves, but device complexity and cost increase
Solution Approach 1:
The actuator housing serves as the magnetic field generator, and the rotary element with its magnet serves as the position indicator. The system uses existing components for measurement rather than adding separate sensors, making the measurement function self-service.
Solution Approach 2:
The rotary element serves dual purposes: it controls the actuator's mechanical function and simultaneously provides position information through its magnetic field interaction with the housing. This multi-functionality eliminates the need for dedicated position sensors.
3Reliability
If the actuator uses a mechanical spring element for emergency parking lock engagement, then the emergency function works without power, but the system requires a latch mechanism to hold the spring
Solution Approach 1:
The latch mechanism is merged with the normal actuator components rather than being a separate emergency system. The latch works together with the spring element and the actuator's existing mechanical structure to provide both normal operation and emergency function through integrated design.
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
Ensures reliable actuator positioning with high measurement accuracy, eliminates the need for additional sensors, and allows engagement of the parking lock under all conditions, including power failures, by using an inductive measuring principle and a mechanical emergency adjustment device.
Implementation Method 1
a coil (14) arranged on a circuit board (13) for inductively determining a position of the position sensor (11)
Implementation Method 2
The emergency function for engaging the parking lock is implemented by a spring element, which is preloaded by actuating the non-parking position of the actuator
Data Source
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AI summary
The invention relates to an actuator having a drive (2) driving an input shaft (1), a first actuation element (3) in operative connection with the input shaft (1) for actuating a shifting mechanism, and a rotatably mounted rotation element which can be driven by means of the input shaft (1) and has a first control cam (7) for controlling the actuating position of the actuator, which control cam is operatively connected to the first actuation element (3) for actuating the shifting mechanism. According to the invention, the actuating position of the actuator can be determined inductively by means of a receiving or holding element (10) for a position indicator (11), said receiving or holding element being operatively connected to the rotation element (4).