Compact Electromechanical Disc Brake Actuator Design
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Solution Overview
Problem
The large size of electromechanical brake actuators in motor vehicles limits their integration into the wheel rim, due to the mechanical power requirements and the need for a significant footprint, which restricts radial space and complicates mounting.
Innovation Solution
The actuator design where the entire motor and majority of the reduction gear extend on the same side of the fixing face along the axis of rotation, allowing the actuator to be housed opposite the caliper body and reducing the overall size, utilizing a brushless motor with rotating windings and an epicyclic gear train for compactness and increased torque delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the motor and gearbox are arranged with the gearbox behind the piston, then the mechanical power transmission is efficient, but the actuator's footprint increases and radial space is restricted
Solution Approach 1:
The patent repositions the motor and gearbox assembly from a longitudinal arrangement (behind the piston) to a radial arrangement (on the same side of the fixing face). This dimensional change allows the actuator to utilize radial space more efficiently, reducing its overall footprint while maintaining power transmission efficiency through the helical linkage mechanism.
Solution Approach 2:
Instead of placing the gearbox behind the piston as in conventional designs, the patent inverts this arrangement by positioning both the motor and gearbox on the same side of the fixing face. This inversion enables the actuator to fit within the available radial space between the rim and brake disc while still delivering the required mechanical power.
2Power
If the motor is made larger to provide required mechanical power, then the power output is sufficient, but the actuator size increases and integration into the wheel rim becomes difficult
Solution Approach 1:
The patent employs a nested arrangement where the gearbox is positioned within the same radial space as the motor, with both components extending on the same side of the fixing face. This nesting approach allows the actuator to deliver sufficient mechanical power through the helical linkage while minimizing its overall volume to fit within the wheel rim constraints.
3Ease of manufacture
If the actuator is positioned to fit within the radial space of the wheel rim, then the integration is simplified, but the motor and gearbox must be compacted which may affect power delivery
Solution Approach 1:
The patent utilizes parameter changes in the gear reduction ratio and motor characteristics to maintain sufficient power delivery despite the compacted size. By optimizing these parameters within the constrained radial space, the actuator achieves both easy integration into the wheel rim and adequate mechanical power output for brake actuation.
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 design facilitates easier integration of the caliper and actuator into the wheel rim by reducing the radial constraints, enabling a more compact and powerful braking system that fits within the available space.
Implementation Method 1
an electric motor and a mechanical reducer coupled to each other and each comprising components rotating around axes parallel to an axis of rotation of the motor
Implementation Method 2
a mechanical reducer coupled to each other and each comprising components rotating around axes parallel to an axis of rotation of the motor
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to an electromechanical actuator (7) for a motor vehicle brake caliper, comprising a casing (8) having a planar face (9) for fixing to a caliper body (1), this casing (7) enclosing an electric motor (19) and a mechanical reduction gear (14) which are coupled to one another and comprise components rotating about axes (AX) of orientation normal to the planar fixing face (9). According to the invention, the reduction gear (14) and the motor (19), as well as the casing (8) all three extend wholly on one and the same side of the planar fixing face (9).