Rotary Connector Cable Layout for Compact Steering Housings
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Solution Overview
Problem
Conventional rotary connector devices for steer-by-wire systems are limited by the need for long flat cables and annular spaces, restricting design flexibility and increasing manufacturing costs due to the requirement for balanced circular movement and sufficient housing volume.
Innovation Solution
A rotary connector device with flat cables wound in one direction on a hollow cylindrical part and a different direction on an outer wall portion of a fixed member, utilizing a non-annular space for cable reversal, reducing cable length and housing volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flat cables are wound along the inner and outer periphery of an annular space to ensure balanced circular movement, then the rotational reliability is improved, but the housing volume and flat cable length increase significantly
Solution Approach 1:
The patent extracts the flat cables from the conventional annular space configuration and repositions them to wind along the outer peripheral surface of the rotary member. This extraction from the traditional annular path allows the cables to follow a more compact route that reduces the required housing volume while maintaining the necessary rotational movement range of approximately 0.5 to 0.8 turns.
Solution Approach 2:
The patent transitions from a two-dimensional annular winding path to a three-dimensional configuration where flat cables wind along the outer peripheral surface of the rotary member. This dimensional change allows the cables to utilize the radial and axial dimensions of the rotary member, creating a more space-efficient arrangement that reduces housing volume requirements.
2Reliability
If an annular space is provided within the housing for flat cables to circulate, then the rotational movement is ensured, but the design flexibility is restricted
Solution Approach 1:
The patent implements a dynamic cable routing system where the flat cables are wound along the outer peripheral surface of the rotary member, allowing the cables to naturally adapt to the rotational movement. This dynamic arrangement eliminates the need for a fixed annular space structure, thereby increasing design flexibility while ensuring reliable rotational movement through the reduced range of approximately 0.5 to 0.8 turns.
3Ease of operation
If the flat cables are made long enough to circulate along the walls of the annular space, then the rotational range is sufficient, but the manufacturing cost increases
Solution Approach 1:
The patent applies preliminary action by pre-winding the flat cables along the outer peripheral surface of the rotary member in a predetermined pattern. This pre-configuration optimizes the cable length required for the reduced rotational range of 0.5 to 0.8 turns, eliminating the need for excessive cable length and thereby reducing material costs and manufacturing complexity.
4Reliability
If the reversal portions of the flat cables are evenly arranged within the annular space, then the balanced circular movement is ensured, but the flat cable length and housing volume increase
Solution Approach 1:
The patent employs asymmetric cable routing where the reversal portions of the flat cables are positioned strategically along the outer peripheral surface of the rotary member rather than being evenly distributed in an annular space. This asymmetric arrangement maintains balanced circular movement for the reduced rotational range while minimizing the total flat cable length required, as the cables follow a more direct path during rotation.
Data Source
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AI summary
This rotary connector device is provided with: a fixed body; a rotating body that has a cylindrical part and is rotatably mounted inside of the fixed body; and one or more flat cables housed in a housing space between the fixed body and the rotating body, wound in one direction on the cylindrical part of the rotating body, and wound in the other direction on an outer wall portion of the fixed body that is disposed opposite only a portion of the cylindrical part of the rotating body.