Rotary Hammer Mode-Linked Trigger Lock for Hammer-Only Use

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Solution Overview

Problem

Rotary hammers lack a convenient mechanism to continuously activate the motor in hammer-only mode without manual trigger depression, limiting user convenience and efficiency.

Innovation Solution

A rotary hammer design featuring a mode selection dial, a lock mechanism, and a linkage system that allows the trigger to be locked in the on position when selecting hammer-only mode, enabling continuous motor operation without manual depression, and switching between full power and variable speed modes based on trigger position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a lock mechanism is added to enable continuous trigger activation, then user convenience and efficiency are improved, but device complexity increases

Engineering Contradiction:
Improveuser convenienceVSAvoiddevice complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The lock mechanism is nested within the existing trigger assembly structure. The shuttle component is received within the trigger housing and integrates with the trigger finger, mode selection dial, and linkage components already present in the rotary hammer. This nesting approach allows the lock mechanism to be incorporated without adding significant external complexity while still providing continuous activation functionality.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The linkage acts as an intermediary component that connects the mode selection dial to the lock mechanism. When the mode selection dial is rotated to hammer-only mode, the linkage moves to a position that enables the shuttle to engage and lock the trigger in the activated position. This intermediary linkage allows the mode selection to control the locking function without direct mechanical coupling between all components.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If the lock mechanism is always available, then continuous operation is enabled, but safety and mode appropriateness are compromised

Engineering Contradiction:
Improvecontinuous operationVSAvoidmode appropriateness
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The lock mechanism is made dynamic through the mode selection dial. The availability of the locking function changes based on the selected mode. In hammer-only mode, the linkage moves to a position that allows the shuttle to engage and lock the trigger for continuous operation. In rotary hammer mode, the linkage position prevents the shuttle from engaging, thereby disabling the lock function and requiring manual trigger activation. This dynamic behavior ensures the lock mechanism is only available when appropriate for the selected mode.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The linkage has different functional states in different positions. When the mode selection dial selects hammer-only mode, the linkage is in a position that locally enables the lock mechanism by allowing the shuttle to engage with the trigger assembly. When rotary hammer mode is selected, the linkage is in a different position that locally disables the lock mechanism. This local quality change based on mode selection ensures the lock function is only active when appropriate.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4257293A1Rotary hammer
Publication Date: 2023.10.11 MILWAUKEE ELECTRIC TOOL CORP
  • EP4257293A1 patent drawingFigure 1
  • EP4257293A1 patent drawingFigure 2~3
  • EP4257293A1 patent drawingFigure 4~6

AI summary

A rotary hammer (10) operable in a first mode in which only a hammering operation to reciprocate a tool bit along a drive axis is performed and a second mode in which the tool bit is rotationally driven about the drive axis. The rotary hammer includes a motor (18), a controller (31) to control operation of the motor, a trigger (30) moveable between an off position and an on position, a mode selection dial (130) operable to select the first or second mode, a lock mechanism moveable between a first position and a second position, a linkage moveable between a third position and a fourth position, and a switch in communication with the controller. The switch communicates with the controller to operate the motor at full power or communicates with the controller to operate the motor at a variable speed based on the position of the trigger between the on position and the off position.