Gearbox Locking Mechanism With Wide-Window Parking Engagement
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Solution Overview
Problem
Conventional parking brake mechanisms have a limited engagement window, resulting in low probability of direct engagement and high likelihood of violent engagement shocks, making them ineffective, especially on slopes and when stopping on horizontal ground.
Innovation Solution
The parking brake device features a slider with internal teeth sliding in external grooves of a hub, engaging between external teeth of a dog clutch, with a reduced number of teeth or notches regularly distributed angularly, increasing the engagement window and likelihood of direct engagement to over 80%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional parking brake mechanisms with notched wheels and fingers are used, then the structure is simple, but the engagement window is very narrow resulting in low probability of direct engagement (around 5%)
Solution Approach 1:
The parking brake mechanism is segmented into distinct functional components: a toothed wheel with multiple notches, a finger with a lug, and a spring-loaded actuation system. The toothed wheel is divided into multiple engagement zones (notches) distributed around its circumference, increasing the angular window for successful engagement from a single narrow point to multiple opportunities during rotation.
Solution Approach 2:
The spring-loaded finger is pre-positioned in a retracted state, ready to engage with the notches. The system prepares for engagement by maintaining the finger in a position where it can automatically engage with any notch that passes by during wheel rotation, eliminating the need for precise timing or manual adjustment during the engagement process.
2Reliability
If the vehicle moves a random distance to achieve engagement, then engagement may be achieved, but the time available for engagement is very narrow and the shock of engagement becomes extremely violent
Solution Approach 1:
A spring mechanism is incorporated into the finger assembly that acts as a cushion during engagement. The spring absorbs and dampens the impact forces when the lug engages with a notch, reducing the violent shock that would otherwise occur during engagement. This cushioning effect protects the mechanical components from excessive stress and damage.
Solution Approach 2:
The engagement mechanism transitions from a single-point engagement (one finger, one notch) to a multi-point engagement system where the toothed wheel provides multiple notches distributed around its circumference. This dimensional expansion from 1D to 2D angular distribution increases the probability of engagement and allows the system to accommodate larger vehicle movements without requiring precise timing.
3Adaptability or versatility
If parking brake mechanisms operate with limited engagement window, then the structure remains simple, but the blocking cases are numerous and the system is ineffective on slopes
Solution Approach 1:
The toothed wheel is segmented into multiple notches distributed around its circumference, creating multiple engagement zones. This segmentation allows the system to remain effective regardless of the wheel's starting position or the direction of movement, making it adaptable to various operating conditions including slopes and horizontal ground.
Solution Approach 2:
The spring-loaded finger assembly automatically positions itself for engagement and executes the engagement action without requiring external control or adjustment. The system serves itself by using the wheel's own rotation to bring notches into alignment with the finger, eliminating the need for complex control mechanisms while maintaining effectiveness on slopes and various surfaces.
Data Source
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AI summary
Gearbox locking device, comprising a pinion (11) rotating idly on a shaft (10) of the gearbox and permanently connected to the vehicle wheels, a fixed claw (13) carried by the casing, a hub (12) rigidly attached to the pinion (11), and a slide (16) sliding on the hub in the direction of the claw, characterised in that the slide (16) has inner teeth (16a) sliding in grooves (12,a) outside the hub (12), and engaging between teeth (13,a) outside the claw (13), to achieve the locking of the gearbox.