Plastic Planet Carrier with Tubular Guide Pins for Parking Brake Actuator
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Solution Overview
Problem
Existing electromechanical actuators for motor vehicle parking brakes with planetary gear trains face challenges in managing high load stresses and bulkiness, leading to increased unsprung mass and dimensioning issues when integrated with disc brakes.
Innovation Solution
A planet carrier for the planetary gear train made of molded plastic material with tubular guide pins and crimped zones, which are elastically deformable, reduces stress absorption and compactness, and an assembly method involving molding and crimping to secure the guide pins, allowing for efficient torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional metallic components are used in the planet carrier, then strength and durability are improved, but weight and bulkiness increase leading to increased unsprung mass
Solution Approach 1:
The patent applies parameter changes by transitioning from metallic materials to molded plastic material for the planet carrier frame. This material parameter change significantly reduces weight while maintaining sufficient strength through optimized geometric design and reinforcement structures integrated into the plastic component.
Solution Approach 2:
The patent employs composite materials by combining molded plastic with metallic inserts or reinforcement elements. The plastic frame provides lightweight structure while integrated metallic components (such as crimped zones, guide pins, or reinforcement inserts) provide localized strength and durability where required by the mechanical loading conditions.
2Volume of moving object
If the electromechanical actuator is made compact, then integration with disc brakes is improved, but stress absorption capability under high load may be compromised
Solution Approach 1:
The patent applies segmentation by dividing the planet carrier into distinct functional zones: a lightweight molded plastic frame for overall structure, separate guide pins for precise planetary gear positioning, and crimped zones for secure assembly. This segmentation allows each component to be optimized for its specific function while maintaining compact overall dimensions.
Solution Approach 2:
The patent implements beforehand cushioning through the design of crimped zones and flexible mounting features that provide elastic deformation capacity. These features are built into the structure during manufacturing to absorb shock loads and stress variations that occur during operation, protecting the compact actuator from damage while maintaining small dimensions.
3Weight of moving object
If molded plastic material is used for the planet carrier, then weight is reduced, but manufacturing precision and assembly difficulty may increase
Solution Approach 1:
The patent applies merging by integrating multiple functions into the single molded plastic frame: structural support, mounting features for guide pins, reinforcement structures, and alignment features for planetary gears. This consolidation reduces the number of separate parts and assembly steps while maintaining manufacturing precision through the capabilities of modern injection molding processes.
Solution Approach 2:
The patent applies local quality by providing different structural characteristics at different locations within the molded plastic frame. Reinforcement ribs, thickened sections, and integrated metallic inserts are placed specifically in areas requiring higher strength or precision, while other areas remain lightweight. This localized optimization maintains manufacturing precision where needed without compromising overall weight reduction.
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
The solution provides a compact and efficient electromechanical actuator with reduced unsprung mass and improved stress absorption, enhancing the integration with disc brakes while maintaining high torque transmission capabilities.
Implementation Method 1
the second axial end which is immobilized axially with respect to the second of the two support plates by at least one crimped area of this second axial end
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The invention proposes a planet carrier (50) for a planetary gear train of a reducing mechanism of an electromechanical actuator for actuating a parking brake of a motor vehicle, which carries planet pinions (52), each of which is accommodated between two parallel support plates (56, 58) belonging to a reinforcement (54) of the planet carrier and each of which is mounted in rotation on the planet carrier (50) about a rotation guide pin (74) that is mounted between the two support plates (56, 58) to which it is linked by the two opposing axial ends thereof, characterised in that each rotation guide pin (74) is a tubular pin.