Segmented Cylinder Motion Conversion Mechanism for Electric Brake Actuators
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Solution Overview
Problem
Existing motion conversion mechanisms for electric brake actuators are costly due to the use of ball screw mechanisms and high processing costs associated with forming internal threads over the entire length of the cylinder, leading to inefficiencies and increased manufacturing costs.
Innovation Solution
A motion conversion mechanism featuring a shaft with an external thread and a cylinder with two internal thread portions separated by a threadless portion, where the threadless portion is longer than the shorter internal thread portion, allowing for efficient torque and axial force distribution and reducing processing complexity, using multi-start or trapezoidal threads to enhance efficiency and strength while lowering costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ball screw mechanism is used for motion conversion, then the efficiency and strength are improved, but the manufacturing cost increases
Solution Approach 1:
The patent replaces the expensive ball screw mechanism with a simpler, cheaper screw mechanism that does not use rolling elements. Although the simpler mechanism has lower inherent efficiency, the overall system achieves cost-effectiveness by eliminating the need for complex ball screw components while maintaining adequate performance through optimized thread design and direct coupling of the motor to the screw shaft.
2Reliability
If the cylinder length is increased to reduce inclination between shaft and cylinder, then the efficiency and strength are improved, but the processing difficulty and manufacturing cost increase
Solution Approach 1:
The cylinder is divided into multiple sections along its length, with internal threads formed only in specific segments rather than continuously over the entire length. This segmentation allows the cylinder to achieve the necessary structural strength and reduced inclination effects without requiring threads over the full length, thereby reducing processing difficulty and manufacturing cost while maintaining adequate efficiency.
3Strength
If internal threads are formed over the entire length of the cylinder, then the strength is improved, but the processing difficulty and manufacturing cost increase
Solution Approach 1:
The internal threading is segmented to occupy only specific portions of the cylinder length rather than the entire length. This provides sufficient thread engagement length to maintain the required strength for force transmission while significantly reducing the complexity and cost of the threading process.
Solution Approach 2:
The cylinder is designed with different structural characteristics at different locations: internal threads are present only in specific regions where force transmission is needed, while other regions have smooth surfaces or different features. This local differentiation optimizes the strength-to-manufacturing-cost ratio by providing threads only where mechanically necessary.
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 configuration results in a high-efficiency, high-strength motion conversion mechanism that can be manufactured at a lower cost, enabling the production of electric brake actuators with improved performance and reduced manufacturing expenses.
Implementation Method 1
a shaft having an external thread and a cylinder having an internal thread that is screwed with the external thread. The motion conversion mechanism converts rotating motion of one of the shaft and the cylinder into linear motion of the other of the shaft and the cylinder
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A motion conversion mechanism (50) includes a shaft (48) having an external thread and a cylinder (78) having an internal thread that is screwed with the external thread. The motion conversion mechanism converts rotating motion of one of the shaft and the cylinder into linear motion of the other of the shaft and the cylinder. The cylinder (78) is provided with two internal thread portions (78b, 78c), each having the internal thread, such that a threadless portion (78d) is interposed between the two internal thread portions in an axial direction.