Gearbox Parking Lock Lever-Spring Design Against Ratcheting
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Solution Overview
Problem
Existing parking lock systems in vehicle gearboxes and reducers are prone to premature deterioration due to 'ratcheting' phenomena, where the latch impacts against a rotating wheel during vehicle movement, causing damage to the wheel, latch, and locking system components.
Innovation Solution
A parking lock system with a first lever connected to a rod, a second lever pivoted by an actuator, and a second spring with a lower restoring force, along with a carriage featuring first and second rollers, absorbs and accumulates pivoting energy to resist ratcheting by ensuring the latch engages only when a wheel hollow is present, using two levers and springs to stabilize the carriage's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the latch is pushed into the locking position during vehicle movement, then the latch engages with the wheel recess, but the latch repeatedly impacts against the rotating wheel causing ratcheting phenomenon and premature deterioration
Solution Approach 1:
The patent introduces a cushioning element (elastic element or damper) between the carriage and the latch to absorb and reduce the impact forces during ratcheting. This beforehand cushioning mechanism protects the latch and wheel from premature deterioration by dissipating the energy of repeated impacts before they reach the critical components.
Solution Approach 2:
The patent introduces an intermediary element (the cushioning mechanism) between the carriage and the latch. This intermediary absorbs and mitigates the harmful impact forces generated during ratcheting, preventing direct transmission of these forces to the latch and wheel, thereby reducing wear and extending component life.
2Reliability
If a compression spring is positioned around the rod to push the carriage into the locking position, then the carriage is cushioned during ratcheting, but the resistance to ratcheting phenomena can still be improved
Solution Approach 1:
The patent modifies the spring constant or pre-load of the compression spring to optimize its cushioning effectiveness. By adjusting these parameters, the spring provides adequate resistance to ratcheting impacts while maintaining the ability to cushion the carriage during normal operation, thereby improving overall reliability without compromising structural integrity.
3Reliability
If the second spring has a restoring force less than the force required to pivot the second lever, then the second lever only pivots when the latch is opposite a hollow in the wheel, but the system complexity increases
Solution Approach 1:
The patent designs the second spring with a restoring force that is intentionally kept below the threshold required to pivot the second lever. This preliminary anti-action ensures that the lever remains in its current position unless specifically actuated by the latch engaging with a hollow in the wheel, thereby preventing unintended movements and improving engagement precision.
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 system enhances resistance to ratcheting, reducing the risk of damage to the wheel, latch, and locking system components by absorbing and dissipating impact forces, thereby increasing durability and reliability.
Implementation Method 1
a second spring positioned between the first lever and the second lever, the return force of the second spring being less than the force required to pivot the second lever, so that pivoting the first lever in a first direction causes the second lever to pivot and engage the latch if it is opposite a hollow in the locking wheel, otherwise compressing the second spring
Implementation Method 2
a latch (3) arranged inside the housing (2), and pivotally mounted around an axis to move from a locking position engaged in a hollow of a locking wheel (4) linked in rotation to an output of the transmission, to an disengaged unlocking position from the hollow; a carriage (5) mounted at the end of a guide rod (6) and sliding to alternately adopt a locking position, in which the carriage (5) forces the latch (3) to pivot into the locking position, or an unlocking position in which the latch (3) is returned by a first spring into the unlocking position
Implementation Method 3
the carriage comprises a first roller and a second roller, each mounted freely rotatable about a pin. The first roller is positioned to be able to roll against the latch when the carriage moves into the locking position, and the second roller is positioned to roll, in counter-support, on a fixed wall of the system, opposite the latch
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A parking locking system for a gearbox or reduction gear transmission comprising: - a latch (3) pivotally mounted to move from a locking position engaged in a recess of a locking wheel (4) rotationally linked to a transmission output, to an unlocking position disengaged from the recess; - a carriage (5) mounted at the end of a rod (6) and sliding to adopt a locking position, in which the carriage forces the latch to pivot in the locking position, or an unlocking position; - a first lever (7) connected to the rod, and pivoting to push or pull the rod (6); - a second lever (11) intended to be pivoted by an actuator;- a second spring (12) positioned between the levers (7, 11), the restoring force of the second spring being less than the force to pivot the second lever, so that the pivoting of the first lever causes that of the second lever and the engagement of the latch if it is in front of a hollow, otherwise the compression of the second spring.;