Door Latch PCB Sealing With Dual Waterproof Housing
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Solution Overview
Problem
Existing door latch devices face issues with long-term lock mechanism functionality due to grease hardening and rust, and insufficient waterproofing of circuit boards, leading to reduced durability and increased component complexity.
Innovation Solution
A door latch device design that integrates a motor-driven cam wheel for single-motor operation of the lock mechanism, combined with a waterproof circuit board housing using external and internal seals to ensure complete waterproofing and reduce component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lock mechanism is maintained in the locked state for long periods, then security is improved, but grease hardens and components rust leading to reduced reliability
Solution Approach 1:
The cam wheel is designed to automatically rotate periodically even when the door is locked, causing the lock mechanism to cycle between locked and unlocked states. This periodic action prevents grease from hardening and prevents rust by keeping moving parts active, while the door remains securely locked throughout the cycling process.
Solution Approach 2:
The system performs preliminary maintenance action by automatically cycling the lock mechanism before problems occur. The cam wheel rotation preemptively prevents grease hardening and rust formation by keeping components in motion, eliminating the need for manual intervention and ensuring the lock mechanism remains reliable.
2Reliability
If the cam wheel rotates to switch the lock mechanism, then locking/unlocking function is improved, but unnecessary sound is generated
Solution Approach 1:
The cam wheel profile is locally optimized with specially designed cam surfaces that reduce impact and noise during rotation. The cam geometry is shaped to minimize sudden movements and impacts on the lock mechanism components, allowing the lock to switch reliably while generating minimal noise.
3Reliability
If the circuit board is housed separately in a waterproof ECU, then waterproofing is improved, but the number of components and mounting steps is increased
Solution Approach 1:
The circuit board is integrated directly into the door latch device housing, merging the previously separate ECU and door latch device into a single unified assembly. The housing itself is designed with built-in waterproof sealing features, eliminating the need for a separate waterproof ECU and reducing the total number of components and assembly steps while maintaining adequate waterproof protection.
Data Source
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AI summary
Provided is a door latch device that can waterproof the entire surface of the circuit board. A door latch device 10 includes: a circuit board 120 electrically connected to an electric component; a first cover 22 that covers an inner surface of a case 20 to form a first housing space 36; a second cover 24 that covers an outer surface of the case 20 to form a second housing space 124 in which the circuit board 120 is housed; a pin hole 156 that establishes communication between the first housing space 36 and the second housing space 124; a pin 136 that is erected from the circuit board 120 and projects to the first housing space 36 through the pin hole 156; a pin holder 146 that covers the periphery of a base of the pin 136 to support the pin 136 with respect to the circuit board 120; an external waterproof seal 126 that waterproofs the second housing space 124 against the outside; and an internal waterproof seal 166 that is disposed between an edge of the pin holder 146 and the pin hole 156 to waterproof a space between the first housing space 36 and the second housing space 124.