Motor Vehicle Door Lock Plastic Housing Design
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Solution Overview
Problem
Motor vehicle door locks with complex and costly designs, featuring a metal lock case and multiple structural elements, are prone to dirt and moisture ingress due to the arrangement of the rotary latch and pawl, which affects operational reliability.
Innovation Solution
A simplified design where the pawl is mounted inside the plastic housing, and the rotary latch is outside, with the plastic housing acting as a main structural element, reducing the need for a separate metal lock case and minimizing exposure to environmental influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal lock case and multiple structural elements are used, then the locking mechanism can absorb forces and provide structural strength, but the device complexity and production cost increase
Solution Approach 1:
The patent combines the lock case and housing into a single integrated plastic housing structure. The housing serves dual functions as both the lock case (accommodating the locking mechanism) and the housing (protecting internal components), eliminating the need for separate metal lock case and housing structures. This merging reduces the number of parts from three structural elements to one, simplifying the overall device complexity while maintaining structural integrity.
2Ease of operation
If the rotary latch and pawl are arranged with openings for engagement, then the locking mechanism can function properly, but dirt and moisture can enter through the openings affecting reliability
Solution Approach 1:
The patent positions the pawl inside the housing and the rotary latch outside, with the pawl's locking arm extending through a minimal opening. The housing structure nested around the pawl protects it from environmental influences, while the rotary latch remains externally accessible for engagement. This nested arrangement minimizes the opening size required for the locking arm, reducing exposure to dirt and moisture while maintaining the necessary locking functionality.
3Reliability
If a separate metal lock case and housing are used, then the locking mechanism is protected, but the weight and production cost increase
Solution Approach 1:
The patent changes the material parameter from metal to plastic for the housing structure. The plastic housing provides sufficient protection for the locking mechanism while being significantly lighter than metal alternatives. This material parameter change maintains the protective function while reducing the weight of the door lock assembly, addressing both reliability and weight concerns simultaneously.
Data Source
AI summary
The invention relates to a motor vehicle door lock, having at least one housing (1) made of plastics material and having a locking mechanism (3, 4) comprising substantially a rotary latch (3) and a pawl (4), wherein the pawl (4) is mounted inside the housing (1) and the rotary latch (3) is mounted on the outside of the housing (1).