Plastic Bevel Gear Actuator with Curved Tooth Flanks
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Solution Overview
Problem
Existing actuator devices for motor vehicles face challenges in being compact, generating large actuating forces or moments, and simplifying assembly, especially in cramped installation situations.
Innovation Solution
The use of a bevel gear system with arched or convex tooth flanks allows for a 60° to 120° angle between the rotation axes of the output and actuating shafts, enabling imprecise alignment and manufacturing with large positional tolerances, and injection molding of bevel gears from plastic to reduce costs and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bevel gears with straight tooth flanks are used, then precise alignment is required for proper operation, but this increases manufacturing complexity and assembly difficulty
Solution Approach 1:
The patent applies curved tooth flanks with arch-shaped profiles instead of straight tooth flanks. The curvature is designed such that the tooth flank has a curvature that initially increases from one axial end to the other axial end and then decreases again. This curved geometry creates a larger contact area between meshing teeth, which compensates for misalignment and allows for larger positional tolerances in the bevel gear assembly, thereby reducing assembly complexity while maintaining proper operation
2Ease of manufacture
If bevel gears with large positional tolerances are designed, then assembly is simplified, but torque transmission capability is reduced
Solution Approach 1:
The curved tooth flanks with arch-shaped profiles increase the contact area between meshing bevel gears. This larger contact area distributes the transmitted force over a broader surface, maintaining adequate torque transmission capability even when larger positional tolerances are permitted in the assembly
Solution Approach 2:
The bevel gears are injection molded from plastic in a way that pre-establishes the curved tooth flank geometry during manufacturing. This preliminary formation of the curved profile ensures that the torque transmission capability is built into the component design itself, allowing the system to tolerate larger positional deviations without compromising force transmission
3Manufacturing precision
If bevel gears are made with curved tooth flanks for tolerance compensation, then alignment requirements are relaxed, but the gear design complexity increases
Solution Approach 1:
The patent replaces traditional mechanical methods of achieving precise alignment (such as complex machining and assembly procedures) with an injection molding process. The curved tooth flank geometry is directly formed during plastic injection molding, substituting a complex mechanical alignment system with a simpler molded component design that inherently compensates for misalignment
Solution Approach 2:
The invention changes the geometric parameters of the tooth flanks from straight to curved profiles. This parameter change in the tooth flank geometry transforms the rigid alignment requirements into a more tolerant design, where the curved shape adapts to variations in positioning while maintaining proper meshing and torque transmission
Data Source
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AI summary
The device (1) has an actuator (2) with an electric motor (9) for driving of an output shaft (10), and an operating shaft (7) for operating an adjusting unit (4) e.g. tumble flap. A bevel gear (11) for transmitting torque between the shafts has a bevel wheel arranged coaxial to a rotational axis (12) of the output shaft. Another bevel wheel of the gear is arranged coaxial to a rotational axis (13) of the shaft (7). The axes enclose an angle (14) of 60 degrees to 120 degrees and one of the wheels has convex tooth flanks, where the wheels are injection molded from plastic.