Electronic Parking Brake Actuator Axial Dimension Reduction
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Solution Overview
Problem
The existing electronic parking brake actuators with coaxially stacked two-stage planetary gear transmission mechanisms have a large axial dimension, requiring significant adjustments and increasing production time and complexity, especially in mass-produced vehicles, which can affect vehicle performance and efficiency.
Innovation Solution
The electronic parking brake actuator features a gearbox with a motor, primary and secondary transmission gear assemblies, and a planetary gear transmission assembly, where the primary and secondary gear assemblies are coaxially arranged with the planetary gear transmission, and the central axes are aligned to reduce axial space requirements, using press-fitting and injection molding for precise assembly and reduced deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a coaxially stacked two-stage planetary gear transmission mechanism is used to achieve sufficient braking torque, then the reduction ratio is improved, but the axial dimension becomes large
Solution Approach 1:
The patent transitions from a coaxial stacked arrangement (one-dimensional axial stacking) to a parallel gear train arrangement where gears are distributed in the radial plane. The first and second planetary gear transmissions are arranged parallel to each other, with their central axes parallel, allowing torque multiplication to occur in the radial dimension rather than extending axially. This dimensional reconfiguration reduces the axial dimension while maintaining the required reduction ratio.
Solution Approach 2:
The patent employs nested planetary gear structures where planet gears are mounted on planet carriers that rotate around sun gears, with ring gears enclosing the entire planetary set. Each planetary gear transmission stage is self-contained with the planet gears nested within the ring gear, allowing compact packaging of multiple gear stages in a parallel configuration rather than requiring axial stacking.
2Power
If a multi-stage planetary gear transmission mechanism is used to achieve high reduction ratio, then the braking function is improved, but the structure becomes complex
Solution Approach 1:
The patent divides the multi-stage transmission into two separate planetary gear transmissions (first and second stages) that are parallel to each other rather than coaxially stacked. Each planetary gear transmission is an independent module with its own sun gear, planet gears, planet carrier, and ring gear. This segmentation allows each stage to be optimized independently and simplifies the overall structural arrangement by eliminating the need for complex coaxial alignment.
Solution Approach 2:
The patent combines the two planetary gear transmissions in a parallel configuration where both stages contribute to torque multiplication simultaneously. The first planetary gear transmission receives input from the motor and outputs to the second planetary gear transmission, creating a merged transmission system that achieves high reduction ratio through the combined effect of both parallel stages rather than requiring sequential axial stacking.
3Power
If a large axial dimension is accepted to achieve sufficient reduction ratio, then the braking torque is improved, but the production time and adjustments increase
Solution Approach 1:
By reconfiguring the gear train from axial stacking to parallel arrangement, the patent enables sufficient braking torque to be achieved within a reduced axial dimension. This dimensional change allows the actuator to fit within standard vehicle assembly tolerances, eliminating the need for time-consuming adjustments during production and installation, thereby improving productivity without compromising braking performance.
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 design simplifies the structure, enhances precision, and improves production and transmission efficiency by reducing the axial dimension, minimizing adjustments and increasing production speed while maintaining performance.
Implementation Method 1
an actuator of the electronic parking brake includes a motor and a transmission mechanism
Implementation Method 2
a planetary gear transmission assembly comprising a planetary gear carrier, a plurality of planetary gears and an output spline, the plurality of planetary gears being rotatably mounted on a first end surface of the planetary gear carrier
Implementation Method 3
using press-fitting and injection molding for precise assembly and reduced deformation
Data Source
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AI summary
The electronic parking brake actuator (100) disclosed by the present invention includes a gearbox body (10), a gearbox cover (20), a motor (30), a first gear (32) provided on the output shaft (31) of the motor (30), a primary transmission gear assembly (40), a secondary transmission gear assembly (50) and a planetary gear transmission assembly (60), wherein the central axis of the first gear (32) is parallel to the central axis of the planetary gear assembly (60) and the central axis of the secondary transmission gear assembly (50), and the central axis of the secondary transmission gear assembly (50) coincides with the central axes of the planetary gear transmission assembly (60). The present invention has the advantages of simpler structure, higher precision, higher production and transmission efficiency.