Disc Brake Actuator Rack-and-Pinion Layout for Lower Drive Torque
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Solution Overview
Problem
Current electromechanical actuators for disc brakes in commercial vehicles are bulky due to multiple components, including cam disks and additional gears, which complicates installation and requires high drive torque for clamping forces, leading to longer actuation times.
Innovation Solution
A compact electromechanical actuator design featuring a continuously adjustable rack and pinion gear system with an offset actuating shaft, allowing for a high drive torque at the beginning of the braking process that decreases as the application force increases, reducing the required drive torque and enabling faster actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a cam disc and additional gearbox are used to achieve high clamping force, then the clamping force is sufficient, but the actuator size increases and installation becomes complicated
Solution Approach 1:
The patent removes the cam disc from the actuator structure, replacing it with a direct rack and pinion drive. This extraction of the unnecessary component simplifies the overall structure while maintaining the ability to generate sufficient clamping force through the offset actuating shaft mechanism.
Solution Approach 2:
The patent combines the functions of the actuating shaft and gear reduction into a single integrated mechanism. The offset actuating shaft directly integrates the reduction function into the drive shaft itself, eliminating the need for a separate gearbox and simplifying the overall actuator structure.
2Force
If a high reduction ratio gearbox is used to generate high clamping force from low motor torque, then the clamping force is sufficient, but the actuation time increases
Solution Approach 1:
The patent implements a dynamically adjustable reduction ratio through the offset actuating shaft mechanism. The reduction ratio varies continuously during the actuation cycle, providing high reduction (and thus high force) when needed while allowing faster actuation when the full clamping force has been achieved, thereby reducing overall actuation time.
Solution Approach 2:
The patent changes the reduction ratio parameter dynamically during operation. By varying the offset distance of the actuating shaft, the system adjusts the effective reduction ratio to match the instantaneous force requirements, optimizing both force generation and actuation speed throughout the braking process.
3Force
If multiple components including cam disc and gearbox are used, then high clamping force is achieved, but the drive torque requirement increases
Solution Approach 1:
By removing the cam disc and its associated force multiplication mechanism, the patent eliminates the need for excessively high drive torque. The direct rack and pinion drive with offset actuating shaft provides a more efficient torque transmission path, reducing the peak torque requirements while maintaining sufficient clamping force.
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 reduces the drive torque required to clamp the brake disc by 25% and shortens the actuation time, while maintaining sufficient clamping force, improving the overall efficiency and compactness of the actuator.
Implementation Method 1
The rack and pinion drive comprises a rack and a drive gear operatively connected to the rack. The rack converts a rotary motion of the drive gear into a linear motion
Implementation Method 2
The actuating shaft, arranged offset from the drive gear, creates a small reduction at the beginning of the clamping process, with the reduction increasing with increasing clamping force
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Electromechanical actuator for a disc brake, in particular for a commercial vehicle disc brake, comprising an electric motor and a gearbox for generating a drive torque and a rotatorably movable actuating shaft (23) operatively connected to the electric motor, wherein the electromechanical actuator has a rack and pinion drive (20) operatively connected to the actuating shaft (23) for actuating a rotary lever (5) of the disc brake.