Vertically Movable Workpiece Support Ratchet Safety Mechanism

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Solution Overview

Problem

Conventional vertically movable workpiece support devices face issues with accidental drops due to failure of the braking mechanism in the motor, leading to uncontrolled lowering of the workpiece support base, and existing safety mechanisms increase costs and occupy more space.

Innovation Solution

A compact safety mechanism using a ratchet wheel and movable pawl, where the pawl is switched to a non-action position by an actuator before lowering, and engages with the ratchet wheel to prevent rotation of the driving sprocket wheel, utilizing a large diameter ratchet wheel and pivotally supporting the sprocket wheel to reduce components and costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a ratchet gear and movable pawl are added to prevent accidental drops, then safety is improved, but device complexity and cost increase

Engineering Contradiction:

ImprovesafetyVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The ratchet wheel is integrated with the driving sprocket wheel to form a single unified component. This merging eliminates the need for a separate ratchet wheel assembly, reducing the number of parts while maintaining the safety function of preventing accidental drops during workpiece support base lowering.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The driving sprocket wheel is designed to serve dual functions: it drives the drive chain for vertical movement of the workpiece support base, and simultaneously acts as the ratchet wheel for preventing accidental drops. This multi-functionality reduces overall device complexity while improving safety.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a ratchet gear and movable pawl are added to prevent accidental drops, then safety is improved, but occupied space increases

Engineering Contradiction:

ImprovesafetyVSAvoidoccupied space

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If an actuator is added to switch the movable pawl to non-action posture, then ease of operation is improved, but device complexity and cost increase

Engineering Contradiction:

Improveease of operationVSAvoiddevice complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The movable pawl is designed to automatically engage with the ratchet wheel through its own weight without requiring an external actuator. The pawl's gravity-induced engagement simplifies the mechanism by eliminating the need for additional actuators, sensors, and control systems while maintaining ease of operation.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Instead of using an actuator to actively disengage the pawl when needed, the design allows the pawl to remain engaged by default and uses the drive chain's upward force to naturally lift and disengage it during normal operation. This inverted approach eliminates the need for complex actuation mechanisms.

Inventive Principle:

Principle #13The other way round (Inversion)

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

Prevents unintended drops of the workpiece support base by blocking the rotation of the driving sprocket wheel, reducing the number of components and space requirements, and allowing for automatic operation without additional sensors, while minimizing noise during normal operation.

Implementation Method 1

a ratchet wheel (38) which has a larger diameter than an outer diameter of the driving sprocket wheel (23a) is concentrically attached to an outer side of the driving sprocket wheel (23a), a movable pawl (39) which engages with the ratchet wheel (38) so as to block the rotation of the ratchet wheel (38) caused by a movement of the drive chain (22a) when the workpiece support base (3) is lowered

Methodology Applied

Scientific EffectRatchet mechanism: Ratchet

Implementation Method 2

a movable pawl (39) which engages with the ratchet wheel (38) so as to block the rotation of the ratchet wheel (38) caused by a movement of the drive chain (22a) when the workpiece support base (3) is lowered

Methodology Applied

Scientific EffectGravitation: Gravitation

Data Source

PatentUS10807844B2Vertically movable workpiece support device

Publication Date: 2020.10.20 DAIFUKU CO LTD

AI summary

A vertically movable workpiece support device has a ratchet wheel with a larger diameter than the outer diameter of a driving sprocket wheel and is concentrically attached to an end surface of a boss portion in the driving sprocket wheel. A pair of left and right bearing members are provided side by side, on a side on which the free end side of a drive chain is horizontally extended with respect to the driving sprocket wheel, so as to sandwich a horizontally extending path section of the drive chain. A movable pawl is pivotally supported between the pair of left and right bearing members and engages with the ratchet wheel to block the rotation of the ratchet wheel caused by the movement of the drive chain when the workpiece support base is lowered. An actuator switches the movable pawl to a non-action position with respect to the ratchet wheel.