Electric Power Steering Bus Bar Press-Fit Structure for Clean Assembly
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Solution Overview
Problem
The existing electric power steering devices require time and effort for manufacturing due to the need for heating end portions for welding and are prone to generating foreign matter during the press-fitting process, which can lead to disengagement and reduced positioning accuracy of the bus bar.
Innovation Solution
The electric driving device and electric power steering device incorporate a bus bar with a plate-like portion and protruding portions that are press-fitted into through holes with inclined inner surfaces, eliminating the need for welding and reducing foreign matter generation by ensuring secure contact and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the end portions of the protruding portions are welded to the bus bar through heating, then the bus bar is securely held on the holder, but time and effort are needed for manufacturing
Solution Approach 1:
The patent replaces the thermal welding process with a mechanical press-fitting system. The protruding portions with ribs are press-fitted into through holes of the bus bar, where the ribs contact the inner surface to provide mechanical interlocking and secure holding without requiring heating or welding operations.
Solution Approach 2:
The patent extracts the heating and welding steps from the manufacturing process, eliminating the need for thermal processing equipment and operations. The holding function is achieved purely through mechanical interference fit between the protruding portions and through holes.
2Ease of manufacture
If the protruding portions are press-fitted into the through holes, then the bus bar is held on the holder without welding, but the ribs are liable to be scraped by the edge of the opening portion generating foreign matter
Solution Approach 1:
The patent applies preliminary protective action by forming an inclined inner surface at the opening portion of the through hole. This inclined surface prevents the ribs from contacting and being scraped by the sharp edge of the opening, thereby preventing foreign matter generation before the press-fitting operation occurs.
Solution Approach 2:
The inclined inner surface acts as a cushioning feature that guides the ribs smoothly during insertion, preventing direct contact between the rib edges and the through hole opening edge, thus cushioning against the generation of shavings and foreign matter.
3Ease of manufacture
If the ribs are scraped by the edge of the opening portion, then foreign matter is generated, but this leads to disengagement and reduced positioning accuracy of the bus bar
Solution Approach 1:
The inclined inner surface provides preliminary protection by preventing rib scraping and foreign matter generation during assembly. This ensures that no shavings are created that could interfere with the positioning accuracy or cause disengagement of the bus bar from the holder.
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 design simplifies the manufacturing process, reduces foreign matter generation, and enhances the secure holding of the bus bar, thereby improving manufacturing efficiency and positioning accuracy.
Implementation Method 1
a first hole inclined inner surface that is inclined in a direction of reducing an inner diameter of the first through hole with respect to the opposed surface from the opposed surface toward an end portion of the first through hole forming portion
Implementation Method 2
a first hole cylindrical inner surface extending from the first hole inclined inner surface to the end portion of the first through hole forming portion with the inner diameter of the first through hole kept constant
Implementation Method 3
the first protruding portion is press-fitted into the first through hole under a state in which the plurality of first ribs are in contact with the first hole cylindrical inner surface
Data Source
Figure 1
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AI summary
Provided is an electric driving device including a first protruding portion protruding from a holder surface. A plate-like portion has an opposed surface opposed to the holder surface. A first through hole in the plate-like portion is defined by a first through hole forming portion formed in a cylindrical shape so as to project from the plate-like portion to a side opposite to the opposed surface. The first through hole has an inner surface including a first hole inclined inner surface that is inclined in a direction of reducing an inner diameter of the first through hole with respect to the opposed surface from the opposed surface toward an end portion of the first through hole forming portion and a first hole cylindrical inner surface extending from the first hole inclined inner surface to the end portion of the first through hole forming portion with an inner diameter of the first through hole kept constant. The first protruding portion is press-fitted into the first through hole under a state in which a plurality of first ribs are in contact with the first hole cylindrical inner surface.