Bowden Cable Contour Design for Motor Vehicle Door Lock Force Reduction
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Solution Overview
Problem
Existing motor vehicle door locks with flexible drive means suffer from increased stress and potential damage due to excessive forces required for the closing aid, leading to reduced functionality and service life, especially in the overtravel position where the drive means works against mechanical stops.
Innovation Solution
A motor vehicle door lock design featuring a drive unit with a predominantly circular contour of constant radius, where the drive means changes direction by up to 15°, and an enlarged radius in the overtravel area, reducing the required drive force and minimizing directional changes, thus reducing stress on the drive means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive means works against mechanical stops in the overtravel position to ensure secure engagement, then the locking reliability is improved, but the force required increases causing stress and potential damage to the drive means
Solution Approach 1:
The patent employs a circular contour with constant radius that guides the drive means through its movement path. This curved guidance path ensures smooth directional changes without sharp angles, reducing stress concentrations on the drive means while maintaining reliable engagement with the mechanical stops in the overtravel position.
Solution Approach 2:
The patent specifies that the drive means changes direction by a limited angle (up to 15° from straight course) during normal operation, and the contour radius is designed to be greater than the distance from the drive means to the rotational axis. This parameter optimization reduces the mechanical stress on the drive means while ensuring reliable locking engagement.
2Adaptability or versatility
If the contour contributes to directional changes throughout the entire movement range, then the drive means can navigate complex paths, but the stress and force requirements increase
Solution Approach 1:
The patent design specifies that the contour contributes to directional changes only in a specific working area of the drive unit, rather than throughout the entire movement range. This localized approach allows the drive means to follow a mostly straight path (within 15° of straight course) while still achieving necessary directional adjustments in critical areas, reducing overall stress.
3Adaptability or versatility
If the drive means undergoes frequent and large directional changes, then the path flexibility is improved, but the service life and functionality are reduced due to increased stress
Solution Approach 1:
The circular contour with constant radius provides smooth, continuous directional guidance for the drive means, eliminating sharp angles and abrupt changes. This curved path geometry reduces stress concentrations and fatigue on the drive means, extending service life while maintaining the flexibility needed to navigate the locking mechanism's movement requirements.
Solution Approach 2:
The patent optimizes the contour radius to be greater than the distance from the drive means to the rotational axis, and limits directional changes to maximum 15° from straight course. These parameter constraints ensure that the drive means experiences minimal stress while maintaining sufficient path flexibility for reliable operation over extended service life.
Data Source
Figure 1
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AI summary
The invention relates to a motor vehicle door lock which is fitted with a rotative drive unit (7, 8), for example, a closing aid (7, 8), and flexible drive means (5, 6) which are connected to the drive unit (7, 8) for functional control. The length of the drive means (5, 6) can be varied in relation to the base (1) and said means is guided at least partially along a contour (13) which co-operates with the drive unit (7, 8). According to the invention, the length of the drive means (5, 6) alters during the transition of the drive unit (7, 8) from its start position to the end position. Also, the drive means (5, 6) undergoes a change in direction (angle a), mainly in relation to the base (1). Essentially the contour (13) does not additionally contribute to the change in direction, or optionally only contributes in a defined working area of the drive unit (7, 8).