Impact Power Tool Decoupling Mechanism
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Solution Overview
Problem
Existing impact power tools face issues with the hammer potentially striking and damaging the transmission components due to excessive axial movement at high torque levels.
Innovation Solution
The impact power tool incorporates a decoupling mechanism, such as a coupler with retaining balls or a coupling ring, that remains engaged at lower torque levels but decouples from the cam ring at high axial displacement, interrupting torque transmission to prevent hammer impact on the transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the hammer is allowed to travel a greater axial distance to deliver higher torque impacts, then the impact power can be increased, but the hammer may strike the transmission components causing damage
Solution Approach 1:
A decoupling mechanism is introduced as an intermediary between the hammer and transmission. This mechanism includes a cam ring with cam grooves, retaining balls, and a coupling ring with splines that act as a mediator to control the interaction between the hammer's axial movement and the transmission output shaft, allowing beneficial impact motion while preventing harmful contact
Solution Approach 2:
The decoupling mechanism is designed to automatically engage and disengage based on the hammer's axial position. When the hammer moves axially during impact operation, the cam balls automatically ride up the cam grooves and trigger the coupling ring to disengage from the transmission output shaft, eliminating the need for external control systems
2Force
If the hammer moves axially to apply rotational impacts at high torque levels, then the torque transmission capability is improved, but the continuous rotational coupling between the transmission output shaft and cam shaft is disrupted
Solution Approach 1:
The coupling between the transmission output shaft and cam shaft is made dynamic rather than static. The coupling ring can transition between engaged and disengaged states based on operational conditions, allowing the system to adapt its connectivity during different phases of operation - continuously coupled during low torque and intermittently coupled during high torque impact delivery
Data Source
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AI summary
An impact power tool includes a transmission output shaft, a rotary impact assembly with a cam shaft, hammer, and anvil, and a tool output shaft rotatable with the anvil. A coupler removably couples the cam shaft to the transmission output shaft. When torque on the tool output shaft is less than or equal to a first threshold, the transmission output shaft, cam shaft, hammer, and anvil rotate together to transmit torque to the tool output shaft. When torque on the tool output shaft is above the first threshold, the hammer moves along the cam shaft away from the anvil by a first distance and applies rotary impacts to the anvil. When the hammer moves along the cam shaft away from the anvil by a second distance greater than the first distance, the coupler decouples the transmission output shaft from the cam shaft, interrupting torque transmission to the tool output shaft.