Vehicle Door Latch Lever Decoupling for Motor-Failure Closing

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Solution Overview

Problem

Existing electrical door latch devices can become stuck in a latch disabled state when the motor fails to operate, preventing the door from closing and compromising security.

Innovation Solution

A door latch device with a manual cancellation mechanism that allows the latch disabled state to be released via a manual operation, independent of the motor, ensuring the door can be closed even in emergencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If an electrical release mechanism is used to cancel the latched state, then the door can be opened electrically with good operability, but if the motor fails to operate, the latch mechanism remains in a latch disabled state and the door cannot be closed

Engineering Contradiction:

Improvedoor opening operabilityVSAvoiddoor closing capability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The release lever is divided into a first lever operated by the motor and a second lever engaged with the latch mechanism, which can operate independently when the motor fails. The cancellation mechanism separates the electrical and manual release paths, allowing the second lever to be repositioned independently to enable door closing even when the first lever is stuck.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The position of the second lever is changed from a coupled state (operating with the first lever) to a retracted state (independent operation) through the cancellation mechanism. This parameter change allows the manual release mechanism to function independently of the failed motor, restoring the ability to close the door.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a mechanical disengagement mechanism is provided as a countermeasure, then the door can be opened manually when the motor fails, but the latch disabled state cannot be canceled and the door cannot be closed

Engineering Contradiction:

Improvedoor opening capabilityVSAvoiddoor closing operability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The cancellation mechanism is prepared in advance to cancel the coupled state between the first and second levers. When the motor fails, this pre-prepared mechanism allows the second lever to be repositioned to a standby position, enabling the door to be closed subsequently. The inner lever is also prepared to transmit force to both the cancellation mechanism and the release mechanism.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the second lever operates in conjunction with the first lever, then the electrical release mechanism functions properly, but when the motor fails, the second lever remains stuck and prevents door closing

Engineering Contradiction:

Improveelectrical release functionVSAvoidoperation independence

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system transitions from a static coupled state (first lever and second lever always operating together) to a dynamic state where the second lever can be independently repositioned to a retracted state. This dynamic capability allows the system to adapt when the motor fails, enabling the second lever to function independently for door closing operations.

Inventive Principle:

Principle #15Dynamics

4Reliability

If a cancellation mechanism is added to release the latch disabled state, then the door can be closed even when the motor fails, but the device complexity increases

Engineering Contradiction:

Improvedoor closing capabilityVSAvoidmechanism structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The inner lever serves multiple functions: it operates the cancellation mechanism to cancel the coupled state, transmits force to the release lever for door opening, and enables the second lever to be repositioned. By making the inner lever multi-functional, the cancellation mechanism achieves complex functionality without proportionally increasing the number of components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The cancellation mechanism is integrated with the existing release mechanism components rather than being a completely separate system. The inner lever combines the functions of operating the cancellation mechanism and the release mechanism, merging multiple functions into a single component to reduce overall complexity.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20260049506A1Door latch device

Publication Date: 2026.02.19 HI-LEX ACT CORP

AI summary

A door latch device is to be attached to a door of a vehicle. The door latch device has a latch mechanism maintaining the door in a closed state, an electric release mechanism canceling a latched state by driving a motor, and a manual release mechanism canceling the latched state by a manual operation. The electric release mechanism includes an electric release lever operated by driving the motor. The electric release lever includes a first lever operated by driving the motor, and a second lever engaged with the latch mechanism. The manual release mechanism includes an inner lever operated by manually operating a vehicle interior operation portion provided inside a vehicle cabin. The door latch device further has a cancellation mechanism canceling a coupled state between the first lever and the second lever by an operation force of the vehicle interior operation portion.