One-Handed Depth Stop Mechanism for Rotary Hammers

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Solution Overview

Problem

Existing adjustable depth stop mechanisms for handheld drills and rotary hammers require two-handed activation to adjust and latch the depth stop element, making it cumbersome for users to set the desired depth with precision and efficiency.

Innovation Solution

A mechanism that allows the depth stop element to be adjusted and latched using one hand by rotating it about its longitudinal axis, with a latch element that is spring-biased and features tooth arrangements for secure engagement, enabling one-handed operation and stable guidance through a circular through hole.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a latch element is used to secure the depth stop element in position, then the depth stop element can be held securely, but the user must use two hands to operate the mechanism (one hand to hold the latch element, another hand to adjust the depth stop element)

Engineering Contradiction:

Improvesecure latching of depth stop elementVSAvoidone-handed operation capability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

Instead of requiring the user to manually hold the latch element in a release position to adjust the depth stop element, the mechanism is inverted so that the latch element automatically releases when the depth stop element is rotated. The spring-biased latch element is disengaged by the rotational movement itself, eliminating the need for manual holding and enabling one-handed operation while maintaining secure latching when engaged.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The latch element is designed to be dynamic rather than static - it can automatically transition between engaged and disengaged states based on the rotational position of the depth stop element. The spring-biased latch element responds dynamically to rotational movement, engaging when the tooth arrangement aligns with the latch element and disengaging when rotated away, allowing seamless one-handed operation.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If the depth stop element is rotated about its longitudinal axis to move it out of the latch position, then the user can adjust the depth stop element with one hand, but the mechanism requires a circular through hole with precise dimensional tolerances

Engineering Contradiction:

Improveone-handed adjustment capabilityVSAvoiddimensional tolerance of through hole

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The through hole is designed with a circular cross-section that closely encloses the depth stop element, creating a guiding constraint. This circular geometry provides natural guidance for rotational movement while maintaining manufacturing feasibility. The curved surface of the through hole works in conjunction with the tooth arrangement to enable smooth rotation and precise positioning without requiring extremely tight dimensional tolerances.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If the tooth arrangement is engaged with the latch element to secure the depth stop element, then the depth stop element is held firmly in position, but the user cannot manually displace the latch element to adjust the depth stop element

Engineering Contradiction:

Improvefirm engagement of tooth arrangementVSAvoidmanual displacement of latch element

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The mechanism inverts the traditional latch operation by allowing the depth stop element's rotational movement to automatically disengage the latch element rather than requiring manual displacement of the latch element. The spring-biased latch element is automatically released when the tooth arrangement is rotated away from its engagement position, enabling easy one-handed adjustment while maintaining firm engagement when the teeth are aligned.

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

Enables users to easily and precisely set the depth with one hand, ensuring secure latching and preventing over-drilling, while maintaining stability and ease of use even after wear, through tactile feedback and secure tooth engagement.

Implementation Method 1

The latch element is held in engagement with the teeth of the tooth arrangement by spring force

Methodology Applied

Scientific EffectSpring force: Spring

Data Source

PatentEP2551065B1Adjustable depth stop mechanism

Publication Date: 2014.10.29 BLACK & DECKER CORP

Figure 1
Figure 2~4

AI summary

An adjustable depth stop mechanism comprises a support element with a through hole for receiving an elongate depth stop element which is provided with a tooth arrangement at at least one surface portion. The tooth arrangement extends in longitudinal direction of the depth stop element and is fixed against displacement in longitudinal direction in a latch position by means of a latch device provided on the support element. The depth stop element can be moved out of the latch position by rotation about its longitudinal axis to a position in which it can be displaced in longitudinal direction with respect to the support element.