Actuating Device for Gear Selection with Dedicated Park Lock Button
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Solution Overview
Problem
In shift-by-wire actuated gear changing transmissions, there is a lack of haptic feedback, leading to potential unintentional engagement of the park lock, especially during rapid shifts between 'D' and 'R' at low speeds, causing unexpected vehicle stops.
Innovation Solution
An actuating device with a separate park lock activation mechanism that disengages the park lock only through a dedicated button, preventing unintentional engagement when shifting, and allowing intuitive operation without visual attention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a shift-by-wire actuation system is used with minimal haptic feedback, then the actuating force and shift travel are reduced, but the risk of unintentional park lock engagement increases
Solution Approach 1:
The actuating device is segmented into two independent functional components: a gear selector device for selecting drive steps (P, R, N, D) and a separate park lock actuating device (button) for engaging/disengaging the park lock. This segmentation allows each component to be optimized independently - the gear selector provides minimal resistance for easy operation, while the park lock button requires deliberate intentional action to prevent accidental engagement.
Solution Approach 2:
A separate park lock button acts as an intermediary control element between the driver and the park lock function. This intermediary requires intentional pressing action to engage or disengage the park lock, providing a deliberate control mechanism that prevents unintentional engagement during normal gear selection operations.
2Ease of operation
If the gear selector device has a short shift travel, then the operation is more ergonomic, but the haptic feedback about shift state is reduced
Solution Approach 1:
The system provides feedback through multiple channels: optical feedback via a gear display showing the current selected drive step, and haptic feedback through distinct tactile sensations when pressing the park lock button (engagement/disengagement states). This compensates for the reduced haptic feedback from the short gear selector travel.
Solution Approach 2:
The park lock button serves as an intermediary that provides clear haptic feedback through its pressing action and tactile resistance, compensating for the minimal haptic feedback from the gear selector's short travel. The button's distinct tactile characteristics provide information about the park lock state without requiring visual attention.
Data Source
AI summary
An actuating device for selection on shift steps of a gear changing transmission. The actuating device comprises a flexible gear selection device (1) with at least two drive step positions, a park lock position and an additional park lock-actuating device (4) for activation of the park lock. When the gear selector device (1) moves out of the park lock position, the gear selector device (1) becomes disengaged while movement of the gear selector device (1) from one of the drive step positions into the park lock position, or beyond the previous park lock position, does not engage the park lock. Engagement of the park lock is only achieved by actuating the additional park lock-actuating device (4). This improves the safety and provides intuitive shifting between the different drive step positions without the need to view the gear selector device. The unintended engagement of the park lock is precluded.