Brake Actuator Ball Screw Misalignment Compensation
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Solution Overview
Problem
Ball screw transmission devices in assisted electric brake systems are rigid and prone to premature wear due to dimensional tolerances, leading to unreliable brake performance and reduced service life.
Innovation Solution
A mechanical transmission device with a ball nut/screw system and a free connection rod with ball-shaped ends, allowing for tilting and parallel offsets between the screw and piston axes, combined with an Oldham coupling for rotational locking and axial offset absorption, ensuring reliable brake fluid transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid ball screw transmission device is used, then the transmission structure is simple and strong, but the guide plane of the piston cannot be adjusted within narrow radial tolerances and premature wearing occurs
Solution Approach 1:
The invention introduces a dynamic adjustment mechanism that allows the guide plane of the piston to be adjusted within narrow radial tolerances. This dynamic capability enables the system to adapt to dimensional tolerances and maintain reliable brake performance throughout service life, resolving the contradiction between structural simplicity and operational reliability.
Solution Approach 2:
The invention changes the physical parameters of the transmission system by introducing adjustable components that modify the radial tolerances of the piston guide plane. This parameter adjustment allows the rigid ball screw transmission to accommodate dimensional variations without premature wearing, maintaining both strength and reliability.
2Device complexity
If dimensional tolerances are not compensated, then the transmission structure remains simple, but lateral constraints cause premature wearing of the transmission
Solution Approach 1:
The invention introduces a dynamic adjustment mechanism that compensates for dimensional tolerances in the ball screw transmission. This mechanism allows the piston guide plane to be adjusted within narrow radial tolerances, preventing lateral constraints and premature wearing while maintaining reasonable structural complexity.
Solution Approach 2:
The invention implements a compensation mechanism that anticipates and counteracts the effects of dimensional tolerances before they cause damage. By providing adjustable guide planes that can accommodate tolerance variations, the system prevents lateral constraints and extends transmission service life.
3Device complexity
If the piston guide plane is not adjustable, then the transmission device is simpler, but it cannot guarantee pressure-generating function throughout service life
Solution Approach 1:
The invention introduces a dynamic adjustment mechanism for the piston guide plane that enables compensation of dimensional tolerances. This adjustment capability ensures the pressure-generating function is maintained throughout service life by keeping the piston properly aligned within the master cylinder bore, justifying the added complexity through improved reliability.
Solution Approach 2:
The invention modifies the adjustable parameters of the transmission system by enabling radial adjustment of the piston guide plane. This parameter change allows the system to compensate for dimensional variations and maintain consistent pressure generation, ensuring reliable brake performance throughout the service life.
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 enhances the flexibility and reliability of brake system actuation, allowing for effective force transmission and maintaining performance even with misalignment, while ensuring the system remains operational in fail-soft mode.
Implementation Method 1
a ball nut/screw transmission for transforming the rotational movement of the electric motor into a translational movement of the piston
Implementation Method 2
the free connection rod comprises ball-shaped ends cooperating with a ball-shaped cup realized in the bottom of the piston and a ball-shaped cup realized in the screw, respectively
Data Source
AI summary
An actuating device of a brake system controlled by a brake pedal and/or a brake management system for supplying brake circuits with pressurized brake fluid includes a master cylinder, an electric motor, a ball/nut screw transmission, a nut, a screw, and a free connection rod. The master cylinder is connected to the brake circuits and has a primary piston. The electric motor is controlled for a braking action. The ball nut/screw transmission is configured to transform rotary movement of the electric motor into a translational movement of the primary piston. The nut is blocked from moving in translation, free to rotate, and driven by the electric motor. The screw is free to move in translation but blocked from rotating. The free connection rod is pressed between a base of the primary piston and the screw in order to transmit a thrust of the screw to the primary piston.