Impact Power Tool Cam Ring Mechanism for Higher Torque
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Solution Overview
Problem
Existing impact power tools face challenges in efficiently transitioning between rotary and impact modes, particularly in achieving high torque output with minimal axial travel of the hammer, and in using stiffer springs without compromising performance.
Innovation Solution
The implementation of a cam ring nested between the cam shaft and hammer, along with angled or curved cam grooves, allows for greater rotational travel of the hammer relative to the cam shaft in the same or smaller axial distance, enabling the use of stiffer springs and achieving higher torque output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a traditional cam mechanism is used, then the structure is simple, but the hammer axial travel is large and torque output is limited
Solution Approach 1:
The patent introduces a cam ring nested between the cam shaft and the hammer. This nested structure allows the hammer to achieve greater rotational travel relative to the cam shaft within the same or smaller axial distance, thereby increasing torque output without requiring excessive hammer axial travel.
Solution Approach 2:
The patent transitions from a traditional single-dimension cam mechanism to a multi-dimensional mechanism by adding the cam ring with angled or curved cam grooves. This enables the hammer to move in both rotational and axial dimensions simultaneously, achieving greater torque output with controlled axial travel.
2Force
If a stiffer spring is used, then the impact force is increased, but the transition between rotary and impact modes becomes less efficient
Solution Approach 1:
The nested cam ring structure provides a mechanical advantage that allows stiffer springs to be used while maintaining efficient transition between rotary and impact modes. The cam ring's angled or curved grooves facilitate smooth hammer movement and decoupling, ensuring that increased spring stiffness does not compromise transition efficiency.
3Force
If the hammer rotational travel is increased, then torque output is improved, but the axial distance required increases
Solution Approach 1:
The cam ring nested between the cam shaft and hammer enables greater hammer rotational travel within the same or smaller axial distance. The angled or curved cam grooves on the cam ring convert axial movement into enhanced rotational movement of the hammer, achieving improved torque output without proportionally increasing axial travel.
Solution Approach 2:
The patent utilizes multi-dimensional motion by introducing the cam ring with angled or curved cam grooves that convert axial displacement into increased rotational travel of the hammer. This dimensional transformation allows the hammer to achieve greater torque output without requiring proportional increases in axial distance.
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
This design enables higher torque output with less axial travel of the hammer, allowing for more efficient operation in impact mode while maintaining stability in rotary mode, and supports the use of stiffer springs for improved performance.
Implementation Method 1
A spring is configured to bias the hammer toward the anvil
Implementation Method 2
the cam shaft defining a first angled or curved (e.g., V-shaped, U-shaped, parabolic) cam groove on an outer surface of the cam shaft
Data Source
AI summary
A rotary impact tool includes a motor and an impact mechanism. The impact mechanism includes a cam shaft with a first cam groove rotatably driven by the motor, a cam ring received over the cam shaft with a second cam groove on its inner surface and a third cam groove on its outer surface, a hammer received over the cam ring with a fourth cam groove on its inner surface, an anvil with an output shaft and configured to be selectively engaged by the hammer, a spring configured to bias the hammer toward the anvil, a first ball received in the first and second cam grooves to couple the cam ring to the cam shaft, and a second ball received in the third and fourth cam grooves to couple the hammer to the cam ring.