Vehicle Door Latch Ratchet Release Force Reduction
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Solution Overview
Problem
The existing vehicle door latch apparatus requires a manual or electric release operation force to disengage the ratchet from the latch, limiting the arrangement of half and full latch engaging portions on the outer circumference, making it difficult to use and increasing the release operation force due to resistive friction and spring elasticity.
Innovation Solution
A vehicle door latch apparatus with a ratchet member and ratchet restraint system that allows the ratchet member to be disengaged from the latch using a release component force, featuring a pole lever and base lever arrangement with a cam biasing spring, enabling independent movement and reduced release operation force by rotating the ratchet restraint between block and release positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the latch is strongly pressed against the ratchet by latch spring and seal member repulsive force, then the door remains securely closed in full-latched state, but the friction force and ratchet spring elasticity create high resistive force against release operation
Solution Approach 1:
The latch mechanism is divided into two distinct engagement positions: full-latched position for secure door closure and half-latched position for controlled release. The ratchet member can selectively engage with either the full latch engaging portion or the half latch engaging portion on the latch outer circumference, allowing the system to segment the locking function into secure holding and easy release modes.
Solution Approach 2:
The ratchet member acts as an intermediary element between the latch and the ratchet restraint. By introducing the ratchet member with its pawl portion that can engage with either full or half latch engaging portions, the system mediates between the strong holding force needed for security and the low release force needed for ease of operation.
2Reliability
If a conventional ratchet restraint mechanism is used, then the ratchet is prevented from rotating in latch releasing direction, but the friction force between ratchet restraint and ratchet significantly increases release operation force
Solution Approach 1:
The ratchet restraint mechanism is designed to be dynamic rather than static. The ratchet restraint can rotate between a block position where it abuts against the ratchet member to prevent rotation, and a release position where it is detached to allow rotation. This dynamic positioning allows the system to provide stability when needed while minimizing friction during release operations.
Solution Approach 2:
The ratchet restraint is preliminarily positioned at the block position to prevent the ratchet member from rotating in the latch releasing direction during normal operation. This preliminary preventive action ensures engagement stability without requiring continuous friction-based restraint, as the geometric constraint is established in advance.
3Device complexity
If only one engaging portion is provided on the latch, then the structure is simple, but the arrangement of half and full latch engaging portions on the outer circumference is limited
Solution Approach 1:
The latch outer circumference is designed with multiple engaging portions (both full latch engaging portion and half latch engaging portion) that serve different functions. The ratchet member with its pawl portion can universally engage with either type of engaging portion, making the latch structure multi-functional while maintaining relative simplicity.
Solution Approach 2:
The latch mechanism employs asymmetric engagement geometries with different engaging portions positioned at different locations on the latch outer circumference. The full latch engaging portion and half latch engaging portion have different geometric characteristics that accommodate different operational requirements, enabling versatile arrangement while maintaining structural simplicity.
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 apparatus allows for easy disengagement of the ratchet from the latch, enabling the use of half and full latch engaging portions on the outer circumference, reducing the release operation force, and ensuring door operation functionality even without electric assistance.
Implementation Method 1
the ratchet restraint can be rotated by manual release operation force or electric release operation force from a block position to a release position, and a cam biasing spring that biases the ratchet restraint toward the block position
Implementation Method 2
The ratchet is also biased in the latch engaging direction by the resilient force of a ratchet spring
Implementation Method 3
The latch is strongly pressed against the ratchet in the full-latched state by being strongly biased in the releasing direction by the resilient force of a latch spring
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A vehicle door latch apparatus according to the invention has: a latch that is engaged with a striker and that is rotatable from an unlatched position to a full-latched over rotating position; a ratchet member that is rotatably supported by a ratchet shaft and that has a pawl portion, wherein the pawl portion is movable between a latch engaging position, where the pawl portion can face a full latch engaging portion of the latch, and a latch releasing position, where the pawl portion is not in contact with the full latch engaging portion, wherein release component force is generated in a latch releasing direction when latch return force is applied in a releasing direction at the latch engaging position, and the ratchet member is pushed out from the latch engaging position to the latch releasing position by the release component force; a ratchet restraint that is arranged on a side of the ratchet member and that can be moved about a pin between a block position and a release position, wherein at the block position, the ratchet restraint abuts against the ratchet member to prevent the ratchet member from moving from a latch engaging position, where the ratchet member engages the latch due to the release component force, to a latch disengaging position, and at the release position, the ratchet restraint is detached from the latch member to allow the latch member to move from the latch engaging position to the latch disengaging position, and the ratchet restraint has a pole lever, wherein the pole lever can be disengaged from the full latch engaging portion by rotating about a connecting shaft in a latch disengaging direction when the ratchet restraint is at the block position.