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In motorcycle headlamp design, ensuring optimal headlamp performance is crucial for rider safety and visibility. There is an efficient optical design workflow for creating a motorcycle headlamp using LucidShape design features. Our focus will be on designing reflector systems based on the MacroFocal design feature, addressing both high beam and low beam functionalities.
ECE Regulations for Motorcycles
The design of motorcycle headlamps must adhere to the Economic Commission for Europe (ECE) regulations, specifically UN Regulation 149, which is based on the older UN Regulation No. 113. These regulations set uniform provisions for the approval of motor vehicle headlamps emitting symmetrical passing beams (low beams) or driving beams (high beams). The regulations introduce various classes such as A(S), B(S), C(S), D(S), and E(S), with specifications in candela (cd) and lux (lx/25) for 12V and 13.2V versions based on the motorization of the motorcycle.
LucidShape software facilitates the checking regarding regulation compliance with the LID Measure Test Table tool, which provides a quick and easy measurement procedure.
In LucidShape, the LID Measure Test Table tool provides a quick and easy measurement procedure.
Overview of CAD Data
The CAD data used in this project originates from a model of a travel motorcycle. The headlamp unit comprises an upper reflector for the low beam, a lower reflector for the high beam, and a frame holding daytime running lights, all covered with an outer lens. First, the data is converted to the *.stl format and then the files are imported into LucidShape CAA V5 Based.
Model of a travel-motorcycle from an Austrian manufacturer for additive manufacturing and game design, obtained from 3dmodels.org
Design Process
Material Assignment
Materials are assigned based on their reflectance and refractive properties:
- Active reflector (purple): 0.8 reflectance, ideal specular
- Sputtered plastics (grey): 0.7 reflectance, Gaussian reflector
- Lens: Röhm 8N Clear (PMMA)
- Bulb gaps: 0.15 reflective Lambertian
- Bulb glass: n=1.5, ideal refractor
- Bulb wire: 0.5 reflectance Lambertian
- Bulb socket: absorber
- H11 sources: cylinder with 1350 lumen (at 13.2V) Lambertian emission
- DRL-sources: 1x1 mm² Lambertian emitters with black body spectrum at 3000K and 20 lm
Simulation Basics
The calibration of the H11 bulb ensures that whatever optical properties for the light bulb are used, the same output flux is obtained. An H11 bulb i.e. without reflectors or housing is simulated with the nominal 1350 lumen, and a full-sphere sensor counts the total flux output. The efficacy factor is then calculated from the fraction of the counted flux output and 1350 lumen.
Low Beam Design
For the low beam, the target regulation is R149 Class DS 13.2V in cd. Using the MacroFocal tool with 7x2 facets, the design starts with an example model MF Low Beam Headlamp. Adjustments were made to achieve the necessary intensity specifications by reducing the beam spread in horizontal direction.
Also, a headlamp outer lens was designed by using the styling surface (A-side) and the ray deviation correction design feature. This step is important to avoid the out lens negatively impacting the beam pattern by causing glare and distortion effects, also degrading the intensity of the beam pattern.
High Beam Design
The high beam design targets R149/R113 Class C(S) Primary headlamp 13.2V in cd. The starting point is a hot spot at 0,0, and adjustments are made to increase the beam spread while keeping the hotspot above 25000 cd.
Daytime Running Lamp Design
The design of the daytime running lamp (DRL) is based on a PS rotational reflector. The positioning and trim operations were handled with CATIA V5 capabilities. The resulting DRL was simulated using Monte-Carlo ray tracing and the resulting photometry was evaluated against the ECE R148 DRL test table.
Analysis
The ECE regulation analysis is conducted using the Test Table feature in LucidShape CAA, ensuring compliance with:
- ECE R149 Class DS 13.2V for low beam
- ECE R149 Class CS primary 13.2V for high beam (with optimization potential)
- ECE R148 for daytime running light
CATIA V5 draft analysis is used to ensure the demoldability of the reflector shape.
For Driver view and Bird’s eye view the single source option is selected, and the position is adjusted based on the desired lamp mounting position. The resulting beam patterns for both low and high beams are reviewed for uniformity.
High beam analysis in LucidShape
Visualization
To check whether the headlamp design satisfies appearance requirements a photorealisitc visualization is carried out using LucidShape CAA’s Visualize module. For the visualization all lighting functions were energized.
Summary and Conclusion
LucidShape tools provide a comprehensive solution for designing motorcycle headlamps. The powerful design features allow engineers develop the most powerful and efficient lamps. Furthermore, the extensive analysis offering allows the efficient checking for regulation compliance, which is important during the design process and at the end for a final verification of performance metrics and regulation requirements.
LucidShape CAA can significantly speed up the design process by leveraging LucidShape’s powerful design features in the CATIA V5 environment. Design features can be combined with CATIA features, allowing the creation of a fully parametrized and updateable model, thereby allowing highly efficient design iterations. Highly repetitive import/export operations are no longer needed, and engineers can concentrate on the design or performance aspects that matter.
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