Reciprocating Saw Counterweight Layout for Forward Cutting Force
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Solution Overview
Problem
Power tools with reciprocating-type drive mechanisms experience movement away from work pieces due to inertia generated by counterweights, which affects cutting performance and efficiency.
Innovation Solution
A vertically-oriented counterweight that rotates in a specific direction within the housing of a reciprocating saw, counterbalancing the inertia of the output shaft and blade, with a curved outer perimeter extending between 90 to 180 degrees, to enhance cutting performance and reduce vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If counterweights are oriented within the power tool housing, then counterbalancing force is provided, but inertia is generated that moves the power tool away from work pieces
Solution Approach 1:
The patent inverts the conventional counterweight orientation by positioning the counterweight such that its inertial force acts in the same direction as the cutting stroke rather than opposing it. This is achieved by orienting the counterweight rotation axis and mass distribution to generate forward-directed inertial force during the power stroke, thereby eliminating the harmful rearward movement away from the work piece while maintaining counterbalancing effects.
2Stability of the object's composition
If counterweights are used to counterbalance forces, then stability is improved, but cutting performance deteriorates due to movement away from work pieces
Solution Approach 1:
The patent inverts the conventional counterweight orientation by positioning the counterweight such that its inertial force acts in the same direction as the cutting stroke rather than opposing it. This is achieved by orienting the counterweight rotation axis and mass distribution to generate forward-directed inertial force during the power stroke, thereby eliminating the harmful rearward movement away from the work piece while maintaining counterbalancing effects.
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
The counterweight arrangement improves cutting efficiency by ensuring the saw and blade move into the work piece at the start of each stroke, reducing vibration and cutting time.
Implementation Method 1
movement of the counterweights may generate inertia that tends to move the power tools away from work pieces while the power tools are operating
Data Source
AI summary
A reciprocating saw includes a housing, a motor, and a drive mechanism. The motor includes an output gear rotatable about a motor axis. The drive mechanism includes a driven gear that engages the output gear and is rotated by the motor. The driven gear has a circumference and is vertically-oriented within the housing. The drive mechanism also includes an output shaft driven by the motor to reciprocate relative to the housing. The drive mechanism further includes a counterweight fixed relative to the driven gear and rotating with the driven gear. The counterweight includes a mass portion having a leading edge, a trailing edge, and a curved outer perimeter extending more than 90 degrees and less than 180 degrees between the leading and trailing edges.