Vehicle Brake Actuator Ball Screw Guide for Stable Nut-Piston Coupling
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Solution Overview
Problem
Existing brake devices for vehicles face challenges in efficiently converting rotational motion from a motor into linear motion of a piston, leading to issues such as coupling release between the nut and piston, axial load transfer to the motor, and complexity in axial alignment.
Innovation Solution
The brake device incorporates a guide mechanism that restricts the rotation of the nut and provides guidance for its rectilinear motion, a cover to maintain axial directionality, a retaining part to prevent loosening between the nut and piston, and a bearing to bidirectionally support axial loads, thereby reducing the need for additional axial alignment assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a ball screw device is used to convert rotational motion to rectilinear motion, then the conversion function is achieved, but the coupling between the nut and piston may be released when the direction of rotational force changes
Solution Approach 1:
The patent introduces a guide as an intermediary component between the nut and piston. The guide includes a guide groove that receives the nut and restricts its movement to only axial direction, preventing the nut from rotating or deviating when the rotational force direction changes. This mediator ensures reliable coupling transmission while maintaining the motion conversion function.
2Force
If the motor is made sufficiently rigid to support axial load from oil pressure reaction, then axial load support capability is improved, but the sizes and weight of motor housing and bearings must be increased
Solution Approach 1:
The patent extracts the axial load support function from the motor by introducing a bearing that is coupled to the cylinder. The bearing specifically supports the axial load generated by oil pressure reaction, allowing the motor to focus solely on providing rotational force. This separation eliminates the need for an oversized motor housing and bearings, reducing overall system weight while maintaining axial load support capability.
3Manufacturing precision
If additional axial alignment assembly products are used to ensure proper alignment, then alignment precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the bearing serve multiple functions: it not only supports axial load but also provides axial alignment for the screw shaft and guide. By designing the bearing with appropriate clearance and geometric constraints, it automatically maintains proper alignment without requiring separate alignment components. This multi-functionality reduces device complexity and cost while ensuring manufacturing precision.
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 solution effectively converts rotational motion into linear motion, reduces costs and weight by minimizing motor support for axial loads, improves NVH performance, and simplifies assembly by eliminating the need for separate axial alignment products.
Implementation Method 1
a nut coupled to the screw shaft through the medium of a ball member and configured to reciprocate in an axial direction of the screw shaft depending on a rotation direction of the screw shaft
Implementation Method 2
a bearing provided within the cylinder, coupled to the screw shaft, and configured to support an axial load when oil pressure is formed within the cylinder
Implementation Method 3
a motor coupled to the cylinder and configured to provide a rotational force, a screw shaft installed within the cylinder and axially rotated by the rotational force of the motor
Data Source
AI summary
Proposed is a brake device for a vehicle including a housing, a cylinder installed within the housing, a motor coupled to the cylinder and providing a rotational force, a screw shaft installed within the cylinder and axially rotated by the rotational force of the motor, a nut coupled to the screw shaft through the medium of a ball member and reciprocating in the axial direction of the screw shaft depending on a rotation direction of the screw shaft, a piston coupled to the nut and moved by being interlocked with the nut, a guide provided within the cylinder and restricting the rotation of the nut and providing guidance to a rectilinear motion of the nut, and a cover coupled to the cylinder and covering the guide.