Lifter Device Unlocking Stroke Reduction via Radial Pawl Press

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Solution Overview

Problem

The existing lifter devices require a large movement amount for unlocking, resulting in a small feed rotation movement of the gear, which increases the stroke required for the unlocking operation of the operation handle.

Innovation Solution

A lifter device with a pinion gear and a rotation control device that includes a lock pawl with a pressed portion at an intermediate radial position, allowing efficient displacement and release from the base gear, and ratchet meshing structures with symmetrical lock pawls for reduced assembly complexity and improved disengagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the lock pawl is disengaged by rotating the operation handle in the existing lifter device, then the lock pawl can be released from the gear, but the rotational movement required for unlocking is large resulting in small feed rotation movement of the gear

Engineering Contradiction:

Improveunlocking operation strokeVSAvoidfeed rotation movement amount of gear

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

A release member is introduced as an intermediary component between the operation handle and the lock pawl. The release member converts the rotational movement of the operation handle into linear movement that directly pushes the lock pawl out of engagement with the gear, eliminating the need for large rotational movement to achieve unlocking

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The existing ratchet meshing structure that requires rotational movement for disengagement is replaced with a push-type release mechanism. The release member directly pushes the lock pawl in the radial direction to disengage it from the gear, substituting the rotational mechanical system with a more efficient linear push mechanism

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If the lock pawl is positioned at the tooth tip of the base gear for meshing, then the locking is achieved, but the displacement required for release is maximized increasing the unlocking stroke

Engineering Contradiction:

Improvelocking functionVSAvoidunlocking stroke

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The lock pawl is given different functional zones: the tip portion engages with the base gear for reliable locking, while the intermediate position in the radial direction serves as the pressed portion for efficient release. This local differentiation allows the same component to optimize both locking reliability and release efficiency

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If symmetrical lock pawls are used in the ratchet meshing structure, then the structure is simplified for manufacturing, but the number of components increases assembly complexity

Engineering Contradiction:

Improvelock pawl manufacturingVSAvoidassembly structure

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The lock pawl is designed with asymmetric features: one end forms outer teeth for meshing with the base gear, while the other end has a pressed portion for engagement with the release member. This asymmetric design reduces the number of symmetrical components needed while maintaining manufacturing simplicity

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS11273732B2Lifter device

Publication Date: 2022.03.15 TOYOTA BOSHOKU KK

AI summary

Pawls in a lifter device have: outer teeth that are rotatably supported by shafts in lock plates and are meshed with inner teeth of a base; and pins that are provided in an intermediate section in the radial direction, between the shaft center of the shafts and the teeth tips of the inner teeth, and are pressed in the rotation direction by a rotation transmittance plate during a release operation.