Hammer Drill Intermediate Shaft Assembly Mode Switching

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Solution Overview

Problem

Existing hammer drills always perform both rotational and hammering actions when the motor is operated, leading to energy wastage and unnecessary vibrations, as they lack a mechanism to selectively engage or disengage the rotational and hammering components based on the required mode of operation.

Innovation Solution

A hammer drill design featuring an intermediate shaft assembly with a connecting part that can be moved between positions to selectively engage or disengage the rotational and hammering components with the motor output shaft, allowing for mode change between drilling-only and hammer drilling modes through a rotatable mode change collar and movable linkage arrangement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a single intermediate shaft is used to rotate both the hollow spindle and crank member, then compactness and reduced weight are achieved, but the drill always performs both rotational and hammering actions causing energy wastage and unnecessary vibrations

Engineering Contradiction:

Improveweight of intermediate shaft assemblyVSAvoidenergy wastage from unnecessary hammering action

Core Design Contradiction:

Weight of moving objectVSLoss of energy

Solution Approach 1:

The connecting part is made movable with respect to both the first and second parts of the intermediate shaft assembly, allowing dynamic reconfiguration of the rotational path. This enables the system to switch between drilling-only mode (rotation through first part only) and hammer drilling mode (rotation through both first and second parts), resolving the contradiction by making the mechanical path adaptable rather than fixed

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The intermediate shaft assembly is divided into separable components: first part, second part, and connecting part. This segmentation allows the rotational connection to be selectively engaged or disengaged between the motor output shaft and the crank member, enabling independent control of hammering action while maintaining the compact single-shaft structure

Inventive Principle:

Principle #1Segmentation

2Shape

If a single intermediate shaft is used to rotate both the hollow spindle and crank member, then compactness is achieved, but the drill always performs both rotational and hammering actions producing unnecessary vibrations

Engineering Contradiction:

Improvecompactness of intermediate shaft assemblyVSAvoidunnecessary vibrations from hammering action

Core Design Contradiction:

ShapeVSObject-generated harmful factors

Solution Approach 1:

The movable connecting part enables dynamic switching between operational modes, allowing the compact single-shaft design to be maintained while eliminating unnecessary vibrations by disengaging the crank member rotation path when hammering action is not required

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

By segmenting the intermediate shaft assembly into movable parts, the design maintains compactness while enabling selective engagement of the hammering mechanism, thus preventing unnecessary vibrations when drilling-only mode is selected

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If the connecting part is made movable to selectively engage first and second parts, then mode change capability is achieved, but device complexity increases

Engineering Contradiction:

Improvemode change capability between drilling-only and hammer drillingVSAvoidcomplexity of intermediate shaft assembly

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The intermediate shaft assembly is segmented into three parts (first part, second part, connecting part) where the connecting part can move relative to the others. This segmentation provides mode change capability while keeping each component relatively simple in structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The connecting part acts as an intermediary element that mediates the rotational connection between the motor output shaft and the crank member. By making this intermediary movable, mode change capability is achieved without requiring complex control mechanisms

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9925653B2Hammer drill

Publication Date: 2018.03.27 BLACK & DECKER CORP

AI summary

A hammer drill comprises a motor including an output shaft, a shaft assembly rotationally engaged therewith, a hollow spindle, and a hammer mechanism comprising a piston arranged for reciprocating motion within the spindle. The shaft assembly comprises a first part carrying a first gear engaged with a gear on the spindle to cause spindle rotation, a second part carrying a crank member to cause piston reciprocation, and a connecting part configured to rotationally interconnect, or disconnect, the first and second parts. In a first position of the connecting part only one of the first and second parts is rotationally engaged with the output shaft to enable rotation of only one of the first gear and the crank member respectively, while in a second position both the first and second parts are rotationally engaged with the output shaft to enable rotation of both the first gear and the crank member.