Electric Power Steering Torque Detection Component Diameter Reduction
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Solution Overview
Problem
Existing electric power steering apparatuses face challenges in reducing the diameters of torque detection components while maintaining mechanical strength, as reducing the diameter of the torque detection concave-convex section affects the torque transmission and leads to plastic torsional deformation.
Innovation Solution
The design includes a male stopper with a smaller diameter groove bottom circle compared to the torque detection concave-convex section, allowing independent reduction of component diameters while ensuring sufficient mechanical strength, and incorporating a step surface to prevent interference during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the diameter of the torque detection concave-convex section is reduced, then the diameters of torque detection components can be reduced, but the mechanical strength is compromised and plastic torsional deformation occurs
Solution Approach 1:
The invention divides the stopper structure into two separate components: a male stopper with smaller diameter for torque detection, and a female stopper with larger diameter for mechanical strength. This segmentation allows each component to be optimized independently for its specific function, resolving the contradiction between reducing component diameter and maintaining mechanical strength.
Solution Approach 2:
The invention applies different diameter specifications to different parts of the stopper assembly. The male stopper has a smaller diameter (first diameter) suitable for torque detection, while the female stopper has a larger diameter (second diameter) providing mechanical strength. This local differentiation of dimensions allows optimization of each region for its specific functional requirement.
2Volume of moving object
If the diameter of the torque detection concave-convex section is reduced, then component diameters can be reduced, but interference during assembly occurs
Solution Approach 1:
By segmenting the stopper into male and female components with different diameters, the invention eliminates interference during assembly. The smaller male stopper fits into the larger female stopper without causing the distal edge to hit opposing surfaces, allowing smooth assembly while maintaining reduced component diameters.
Solution Approach 2:
The stepped surface structure acts as an intermediary feature that guides the assembly process. The first step surface and second step surface provide intermediate positioning stages that prevent direct interference between the distal edge of the torque detection sleeve and opposing surfaces during assembly.
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 approach enables easy reduction of component diameters while preventing plastic torsional deformation and improving assembly by ensuring the distal edge of the torque detection sleeve does not hit opposing surfaces, thus enhancing mechanical strength and assembly efficiency.
Implementation Method 1
an impedance change is caused in a coil of the torque detection coil unit 31. On the basis of this impedance change, the direction and the size of the torque can be detected.
Implementation Method 2
the torsion bar 19 is prevented from excessively twisting... the torsion bar 19 is elastically twisted (within the given angle range) in accordance with the direction and the size of this torque.
Implementation Method 3
The male stopper 24 and the female stopper 21 are engaged with each other in a concave-convex engaging manner (like a loose spline-engagement) so as to be relatively rotatable within a given angle range
Data Source
AI summary
An electric power steering apparatus includes an input shaft, an output shaft, a torsion bar coaxially coupling the input and output shafts to each other, and a torque detection sleeve. One of the input and output shafts includes a cylindrical portion. On the inner peripheral surface of the cylindrical portion, a female stopper is provided. The other of the input and output shafts includes a male stopper to be engaged with the female stopper, and a torque detection concave-convex section adjacent to the male stopper in the axial direction. The male stopper includes a plurality of male grooves. The torque detection concave-convex section includes a plurality of detection grooves. The torque detection sleeve is arranged radially outside the torque detection concave-convex section. The diameter of a groove bottom circle of the male stopper is smaller than the diameter of a groove bottom circle of the torque detection concave-convex section.