Optical Module Cut-off Mechanism Motor Resistance
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Solution Overview
Problem
The existing cut-off mechanisms in optical modules for motor vehicle headlamps face issues with high self-heating due to low armature resistance in small motors, leading to potential damage from excessive heat, and existing solutions like electronic cards or metal casings are either expensive or cumbersome.
Innovation Solution
A cut-off mechanism with a motor having an armature resistance between 25 and 120 ohms, achieved by increasing the length of the conductive wire while reducing its cross-section, allowing for a more efficient power dissipation and reduced self-heating, without the need for an electronic card, and using a larger motor with a higher armature resistance within the constraints of the optical module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small motor is used to reduce the size of the cut-off mechanism, then the volume available for coils is reduced, but the armature resistance becomes too low (below 25 ohms) causing high current and excessive self-heating
Solution Approach 1:
The patent changes the electrical parameters of the motor by increasing the armature resistance to between 25 and 120 ohms. This is achieved by using a longer, thinner conductive wire in the armature coils, which reduces the current intensity and power dissipation, thereby controlling the self-heating temperature while maintaining a compact motor size
2Temperature
If the armature resistance is increased to reduce current intensity and self-heating, then the length of conductive wire must be increased, but the motor dimensions are constrained by the available space in the optical module
Solution Approach 1:
The patent optimizes the geometric parameters of the conductive wire by increasing its length while reducing its cross-sectional area. This allows the armature resistance to be increased to the optimal range of 25-120 ohms without significantly increasing the motor's external dimensions, as the wire is wound more densely within the same coil volume
Solution Approach 2:
The patent uses a standardized motor design with optimized winding patterns that replicate efficient wire routing. By copying proven winding geometries and optimizing the turn density, the patent achieves higher resistance within constrained dimensions without requiring custom wire layouts
3Weight of stationary object
If a plastic casing is used for the motor, then the cost and weight are reduced, but the casing may be damaged by high temperatures from motor self-heating and environmental heat
Solution Approach 1:
The patent changes the thermal parameters by limiting the motor self-heating temperature to between 15-90°C through optimized armature resistance. This ensures the total operating temperature remains below the degradation threshold of plastic materials (around 220°C), allowing the use of lightweight plastic casings like PES, PET, or PBT that resist temperature damage
Solution Approach 2:
The patent uses plastic materials with specific thermal resistance properties for the motor housing. These plastics are selected to withstand the controlled temperature range while providing adequate thermal insulation, creating a composite solution that combines lightweight structure with thermal protection
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 reduces the intensity of current through the motor, lowers self-heating temperatures, and allows for a plastic motor housing that can withstand the temperatures, eliminating the need for expensive electronic components and heavy metal casings.
Implementation Method 1
the intensity of the current which passes through the motor is high and the latter is therefore required to dissipate a lot of power, which leads to significant self-heating of the motor
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The mechanism (5) has a housing (100), and a driving motor including armature resistance and arranged to cause movement of a light beam cutoff shield, where the housing is made of a plastic material and the armature resistance lies between 25 and 120 Ohms. A pinion of the motor drives the cutoff shield through a gear, where a rotational angle of the shield is lower than a rotational angle of the pinion. The shield includes a tilted portion with respect to a foreground in a rotation according to an axis parallel with a rotational axis of the shield.