Torque Sensor Nested in Lock Nut for Compact Power Steering Assembly
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Solution Overview
Problem
The existing torque detection structures for power steering devices face challenges in assembling workability and device downsizing due to the dimensional relationship between the torque sensor and the fixing member, leading to increased size and complex assembly processes.
Innovation Solution
A torque detection structure is designed with a ball bearing and a fixing member that allows the torque sensor to have an outside diameter smaller than the fixing member's inside diameter, enabling radial overlap and facilitating assembly by allowing the fixing member to pass around the torque sensor, thus reducing the device's size and improving workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the torque sensor outside diameter is set greater than the fixing member inside diameter, then the torque sensor can be assembled first, but the device size increases and assembly complexity increases
Solution Approach 1:
The torque sensor is positioned inside the fixing member by setting the torque sensor outside diameter smaller than the fixing member inside diameter, allowing the fixing member to pass around the torque sensor and enable both components to be assembled in one direction without interference
Solution Approach 2:
The invention changes the dimensional relationship from radial overlap (torque sensor outside diameter greater than fixing member inside diameter) to axial arrangement (torque sensor inside the fixing member), allowing all components to be assembled from one axial direction
2Adaptability or versatility
If the torque sensor and fixing member are arranged axially in series, then the dimensional relationship is satisfied, but the housing size increases
Solution Approach 1:
The torque sensor is nested within the radial space of the fixing member, allowing both components to occupy the same axial region and thereby reducing the overall axial length of the housing
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 avoids mutual interference between the fixing member and the torque sensor, enabling a compact design, improved assembly efficiency, and reduced device size by allowing all components to be assembled in one direction without reversing the housing.
Implementation Method 1
a ball bearing having an inner race, balls, and an outer race and inserted from the one axial opening and accommodated and disposed in the housing for rotatably supporting the output shaft in the housing
Implementation Method 2
a torque sensor having an outside diameter set less than an inside diameter of the fixing member and configured to generate an electrical signal that changes in accordance with an amount of torsional deformation of the torsion bar
Data Source
AI summary
A ball bearing for rotatably supporting a steering shaft, which is comprised of an input shaft and an output shaft connected to each other via a torsion bar is secured by a lock nut. The lock nut has an inside diameter Y1 greater than a maximum outside diameter X6 of the sensor body of a torque sensor mainly configured from a permanent magnet, first and second yoke members, and a magnetic sensor, which are disposed on the outer periphery of the steering shaft. With this configuration, the torque sensor and the lock nut radially overlap with each other, thus reducing the size of a device. Also, because of the lock nut being assembled so as to pass through the outer peripheral side of the torque sensor, component parts can be installed from one direction, thus improving the assembling workability of the device.