Multi-shaft Drive Device with Pinion Case Restriction
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Solution Overview
Problem
Existing multi-shaft drive devices for electric vehicle seats face challenges in protecting the rack and pinion from operation load input, which can lead to damage when the rotation angle of the rotation shaft is restricted by the selector contacting the case.
Innovation Solution
A multi-shaft drive device design that includes a single motor, an input side gear, an output side gear, a selector with a rack, a rotation shaft with a pinion, and a restriction portion that prevents operation force input from being borne by the rack and pinion by restricting the rotation angle of the rotation shaft, either through a contact portion on the case or a contact portion inside the case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rotation angle of the rotation shaft is restricted by the selector contacting the case, then the selector can be positioned accurately, but operation force input is borne by the rack and pinion causing damage
Solution Approach 1:
A restriction portion is introduced as an intermediary element between the rotation shaft and the rack-pinion-selector system. This restriction portion absorbs the operation force input, preventing it from being transmitted to the rack and pinion while still enabling the selector to contact the case for positioning. The restriction portion acts as a mediator that decouples the harmful force path while preserving the positioning function.
Solution Approach 2:
The harmful function (transmission of operation force to rack and pinion) is extracted from the system by introducing the restriction portion. The restriction portion selectively allows the positioning function (selector contacting case) while blocking the harmful force transmission path, effectively separating the useful function from the harmful effect.
2Reliability
If a restriction portion is added to protect the rack and pinion, then damage is prevented, but device complexity increases
Solution Approach 1:
The restriction portion is designed with localized functionality, concentrating the protection function in a specific region of the device. Rather than redesigning the entire system, the restriction portion is added as a targeted local feature that provides protection only where needed (at the rotation shaft interface), minimizing the impact on overall device complexity.
Solution Approach 2:
The restriction portion introduces asymmetric constraints to the rotation shaft, allowing rotation in one direction while restricting it in another. This asymmetric design enables the protection function without requiring symmetric additions to the device, thereby reducing the increase in overall complexity.
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
The design effectively protects the rack and pinion from operation load input, preventing damage and maintaining the external design integrity of the multi-shaft drive device.
Implementation Method 1
a rotation shaft (16) that is provided with a pinion (17) which enmeshes with the rack (18)
Implementation Method 2
an output side gear which is capable of projecting forwards and retreating with respect to the input side gear, thereby selectively enmeshing with the input side gear
Data Source
AI summary
The present invention obtains a multi-shaft drive device that can protect a rack and pinion from operative load input to a selector. The multi-shaft drive device is provided with: an input-side bevel gear (52) to which motor power is transmitted; and an output-side bevel gear (34) that transmits the power transmitted from the input-side bevel gear (52) to a movable mechanism. The multi-shaft drive device is further provided with: a selector (10) that connects/disconnects the meshing of the output-side bevel gear (34) and the input-side bevel gear (52); and a rotating shaft (16) that causes the selector (10) to slide via a rack (18) and pinion (17). Furthermore, the angle of rotation of the rotating shaft (16) is regulated by the end of the pinion (17) contacting a vertical wall (1A) of a case (1).