Nested Torque Sensor in Annular Electric Motor
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Solution Overview
Problem
Existing electric power steering apparatuses face challenges in reducing size in both radial and axial directions due to the omission of speed reduction mechanisms, which necessitates a high-power, large-sized electric motor, leading to increased size in the axial direction.
Innovation Solution
The apparatus incorporates an annular rotor and stator electric motor with a torque sensor disposed within the rotor core's inner space, eliminating the need for a speed reduction mechanism and allowing for reduced axial size, while maintaining power transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a speed reduction mechanism is omitted to reduce radial size, then radial dimension is reduced, but axial size increases due to larger electric motor
Solution Approach 1:
The torque sensor is nested within the inner space of the rotor core, allowing it to occupy space that would otherwise be empty. This nested arrangement enables the torque sensor to share the axial space with the electric motor, thereby reducing the overall axial dimension without compromising the radial size reduction achieved by omitting the speed reduction mechanism.
2Ease of manufacture
If torque sensor is disposed outside the electric motor frame, then torque sensor installation is simplified, but axial size increases
Solution Approach 1:
The torque sensor is merged with the electric motor structure by disposing it within the rotor core's inner space. This integration allows the torque sensor to be part of the motor assembly, sharing the same axial space and thereby reducing the overall axial dimension while maintaining manufacturability through coordinated design of the motor and sensor components.
Solution Approach 2:
The torque sensor is nested within the rotor core, utilizing the inner space of the rotor core for torque sensor placement. This nested configuration allows the torque sensor to be housed within the motor structure itself, reducing the need for additional external space and thereby decreasing the axial dimension of the overall apparatus.
3Power
If high-power electric motor is used to compensate for omitted speed reduction mechanism, then power transmission efficiency is improved, but device size in axial direction increases
Solution Approach 1:
The torque sensor is nested within the rotor core's inner space, allowing it to occupy space that would otherwise be unused. This nested arrangement enables the system to accommodate the high-power electric motor necessary for direct drive while keeping the axial dimension reduced, as the torque sensor shares the axial space within the motor 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 reduces the apparatus's size in both radial and axial directions, enabling effective power transmission and absorption stroke for shock absorption, while preventing electromagnetic interference through the use of an electromagnetic shielded rotor core.
Implementation Method 1
preventing electromagnetic interference through the use of an electromagnetic shielded rotor core
Data Source
AI summary
A vehicle steering apparatus includes a steering member; a steering shaft connected to the steering member; a torque sensor for detecting a steering torque inputted into the steering member; and an electric motor for generating power that is transmitted to the steering shaft based on the steering torque detected by the torque sensor. The electric motor includes an annular rotor and an annular stator. The annular rotor includes an annular rotor core which coaxially surrounds the steering shaft and is rotatable together with a part of the steering shaft. An annular accommodation space is formed between an outer circumference of the steering shaft and an inner circumference of the annular rotor core, and at least a part of the torque sensor is disposed within the annular accommodation space.