Electromechanical Actuator with Nested Rotor and Linear Drive
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Solution Overview
Problem
Existing electromechanical actuators for hydraulic braking systems lack a compact and robust design capable of fast response and high pressure increase, which is essential for efficient operation in a wide range of applications, including vehicle stability control and hill hold functions.
Innovation Solution
The design incorporates an electric motor with a stator and rotor, featuring a rotating lead-screw and linearly translating nut assembly, where the rotor is supported by a four-point contact bearing assembly, allowing for compact packaging and high axial load capacity, and includes a tapered interface for efficient torque transmission and self-centering, along with a resilient end stop to prevent binding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a traditional electromechanical actuator design is used, then the structure is simpler, but the response time is slower and pressure increase capability is reduced
Solution Approach 1:
The linear actuator components (shaft, drive nut, balls) are nested within the rotor body, with the shaft located within the rotor bore and the drive nut moving along the shaft within the enlarged bore portion. This nesting arrangement compactly packages the linear actuator functionality within the motor structure, enabling fast response and high pressure capability without proportionally increasing overall device complexity.
2Force
If the rotor is fully supported along its length, then the structural stability is improved, but the axial load capacity and rapid movement capability are reduced
Solution Approach 1:
The rotor support structure is segmented into two functional zones: an enlarged bore portion (first portion) that accommodates the moving drive nut and allows rapid axial movement, and a reduced bore portion (second portion) that provides structural support through bearing assemblies. This segmentation enables the rotor to achieve both high axial load capacity and rapid movement capability by distributing different functions to different segments.
3Volume of moving object
If a compact design is implemented, then the space efficiency is improved, but the handling of high loads may be compromised
Solution Approach 1:
The motor and linear actuator are merged into a single integrated assembly, with the linear actuator components housed within the motor rotor. The motor housing serves as the actuator housing, and the rotor simultaneously provides both motor rotation and linear actuator guidance. This merging eliminates the need for separate motor and actuator housings, achieving compact packaging while maintaining high load handling capability through the robust integrated structure.
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 configuration enables a compact, robust, and efficient electromechanical actuator that can handle high loads and rapid movement, enhancing the performance of hydraulic braking systems by providing fast response and high pressure increase, suitable for various applications.
Implementation Method 1
The two grooves are filled with metal balls and the balls act on the screw to create a linear movement of the screw relative to the stator
Implementation Method 2
an electromechanical actuator for use in a hydraulic braking circuit of a vehicle comprising: an electric motor having a stator and a rotor
Data Source
AI summary
An electromechanical actuator for use in a hydraulic braking circuit of a vehicle comprises an electric motor having a stator and a rotor, and a linear actuator that is located within the motor. The linear actuator comprises an elongate shaft having a screw part at one end carrying an external thread that extends along a portion of the shaft, and a fixing part at the other end shaft, the linear actuator further comprising a drive nut that surrounds the screw part of the shaft and is located at least in a retracted position inside the enlarged bore of the first portion of the rotor body, the drive nut and being connected to the screw part. The rotor body is secured relative to the stator by a bearing assembly that is fixed to the second part of the elongate rotor body, the other end of the rotor body being otherwise unsupported and overhung from the bearing assembly.