Reciprocating Saw Scotch Yoke Layout for Compact Low-Vibration Drive
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Solution Overview
Problem
Existing reciprocating saws face challenges in minimizing vibration and achieving a compact design due to the constraints of traditional drive mechanisms, which affect their efficiency and assembly processes.
Innovation Solution
The implementation of a dual-eccentric scotch yoke mechanism that includes a spindle and counterweight, arranged above the motor, allowing for a more compact design by optimizing the reciprocating motion and reducing overall tool length, while also simplifying the assembly process through separate subassemblies for the gear case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a traditional drive mechanism is used in reciprocating saws, then the structure is simpler to manufacture, but the tool length is longer and vibration is not effectively reduced
Solution Approach 1:
The spindle is positioned to extend into the space between the first and second vertical planes defined by the motor faces, effectively nesting the spindle within the motor's spatial envelope. This allows the reciprocating mechanism to be compacted without increasing the overall tool length, while the dual-eccentric scotch yoke mechanism provides the necessary vibration reduction functionality.
Solution Approach 2:
The patent utilizes the vertical dimension by positioning the spindle to extend into the space between the motor faces along the motor axis. This three-dimensional arrangement allows the drive mechanism components to be stacked vertically rather than arranged linearly, reducing the horizontal tool length while maintaining functional effectiveness.
2Object-affected harmful factors
If a dual-eccentric scotch yoke mechanism is implemented, then vibration is reduced and compact design is achieved, but the assembly process becomes more complex
Solution Approach 1:
The gear case is divided into separate subassemblies, allowing the dual-eccentric scotch yoke mechanism to be assembled and tested independently before integration into the complete saw. This modular approach simplifies manufacturing by enabling parallel assembly of components and reduces the complexity of final assembly, despite the intricate nature of the vibration-reduction mechanism.
3Length of moving object
If the spindle is positioned to extend into the space between motor faces, then a compact design is achieved, but the motor space for other components is reduced
Solution Approach 1:
The spindle is nested within the spatial envelope defined by the motor faces, extending into the vertical space between them. This efficient use of available volume allows the reciprocating mechanism to be integrated without increasing the external dimensions of the motor housing, achieving compactness while maintaining necessary component clearance.
Solution Approach 2:
The arrangement transitions from a horizontal layout to a vertical stacking arrangement, utilizing the dimension along the motor axis. This allows the spindle and reciprocating components to occupy vertical space rather than horizontal space, effectively packing more functionality into the same external footprint without interfering with motor operation.
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 solution effectively reduces vibration, achieves a more compact saw design, and decreases assembly time and costs by allowing for a more efficient packaging of components and streamlined assembly procedures.
Implementation Method 1
The scotch yoke mechanism includes a counterweight driven to reciprocate relative to the motor and opposite to the spindle
Data Source
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Figure 5
AI summary
A reciprocating saw including a motor defining a motor axis, the motor including a front end and a back end, the front end including a front face defining a first vertical plane, and the back end including a rear face defining a second vertical plane parallel to the first vertical plane. The reciprocating saw also includes a dual-eccentric scotch yoke mechanism coupled to the motor. The scotch yoke mechanism includes a spindle driven to reciprocate relative to the motor along a spindle axis parallel to the motor axis, the spindle including a rear end nearest to the motor. The scotch yoke mechanism also includes a counterweight driven to reciprocate relative to the motor. The spindle is arranged above the motor. As the spindle reciprocates forward and backward, the rear end extends into a space defined between the first and second vertical planes.