Vehicle Brake Actuator with Irreversible Threaded Rollers
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Solution Overview
Problem
Electromechanical braking actuators with ball screws suffer from reversibility issues, compromising braking reliability and safety, and are costly due to complex manufacturing requirements.
Innovation Solution
A braking actuator with a screw and internal casing connected via an irreversible mechanism, utilizing threaded rollers with opposite thread orientations to prevent unintended movement and reduce manufacturing costs, featuring a double-stage reduction mechanism for improved efficiency and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ball screw is used in the electromechanical braking actuator, then the manufacturing cost is reduced, but the reversibility issue compromises braking reliability and safety
Solution Approach 1:
The patent inverts the conventional ball screw design by using a screw with a single unidirectional thread instead of a bidirectional ball screw. This inversion eliminates reversibility while simplifying the manufacturing process, as the single-threaded screw can be produced more easily than precision ball screws.
Solution Approach 2:
The patent extracts and eliminates the ball component from the ball screw mechanism, retaining only the threaded screw and casing. This removal of the ball element simplifies the structure and manufacturing while achieving the desired irreversible mechanical advantage for braking applications.
2Device complexity
If a ball screw is used in the electromechanical braking actuator, then the structural complexity is reduced, but the manufacturing cost increases due to complex manufacturing requirements
Solution Approach 1:
The patent inverts the conventional approach by using a simpler single-threaded screw design instead of a complex ball screw. This inversion achieves lower structural complexity and lower manufacturing cost simultaneously, as the unidirectional thread is easier to manufacture than precision ball screws.
3Ease of manufacture
If a high-speed electric motor is used, then the cost is reduced, but the reduction capacity requires improvement to achieve the necessary braking force
Solution Approach 1:
The patent segments the reduction mechanism into multiple threaded rollers arranged around the screw, each contributing to the mechanical advantage. This segmentation allows the use of a simpler, lower-cost motor while achieving the necessary total reduction capacity through the combined effect of multiple rollers.
Solution Approach 2:
The threaded rollers serve multiple functions: they provide mechanical advantage through threading, guide the motion of the screw, and distribute the load. This multi-functionality allows a simpler motor to achieve the required power output without needing high-speed, high-cost motors.
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
Enhances braking reliability and safety by eliminating unintended movement, reduces costs through simpler components, and allows for the use of low-cost, high-speed electric motors, achieving a reduction ratio of up to 1/180.
Implementation Method 1
threaded inner rollers, the inner rollers each being engaged on the one hand with the screw and on the other hand with the inner casing by means of at least one thread
Implementation Method 2
the external rollers being provided with at least one thread oriented in the opposite direction to a thread of the internal casing and in the same direction as a thread of the external casing
Implementation Method 3
a screw, a threaded internal casing in engagement with the screw by means of an irreversible connection
Data Source
Figure 1~2
Figure 3~5
AI summary
The vehicle brake actuator (10) comprises: - a screw (12), - a tapped internal casing (18) in mesh with the screw (12) by means of an irreversible connection, - an electric motor (M) commanding a movement of the screw (12) with respect to the internal casing (18) or of the internal casing with respect to the screw so that this movement actuates a brake element (E), - threaded internal rollers (14), the internal rollers (14) each being in mesh firstly with the screw (12) and secondly with the internal casing (18) by means of at least one thread (14A), - a tapped external casing (30), and - external rollers (28) each in mesh firstly with the internal casing (18) and secondly with the external casing (30), the external rollers (28) being provided with at least one thread (28A) of opposite hand to a thread (18A) of the internal casing (18) of the same hand as a thread (30A) of the external casing (30).