Saber Saw Motion Converter With Eccentric Pendulum Drive
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Solution Overview
Problem
Hand-held machine tools, particularly saber saws, face issues with high empty weight, complex and costly motion converter structures, and inefficient energy use due to existing designs, making them difficult to handle and operate effectively in tight spaces.
Innovation Solution
A hand-held machine tool with a motion converter that utilizes an eccentric element and a pendulum element with a guide element to convert rotational motion into a reciprocating motion, featuring a worm drive, needle bearing, and an eccentric counterweight for reduced friction and improved cutting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional motion converters (wobble plate, eccentric drive with multiple connecting rods) are used, then rotational motion can be converted to reciprocating motion, but the device becomes complex, heavy, and costly
Solution Approach 1:
The motion converter is divided into distinct functional elements: an eccentric element that generates elliptical motion, a guide element that constrains the motion direction, and a pendulum element that converts it to reciprocating motion. This segmentation allows each component to be simple and robust while collectively achieving the desired motion conversion.
Solution Approach 2:
The patent extracts and eliminates unnecessary intermediate components from conventional designs. Instead of using multiple connecting rods and complex linkages, only the essential elements (eccentric element, guide element, pendulum element) are retained, significantly simplifying the structure while maintaining functionality.
2Ease of operation
If conventional motion converters with multiple linkages are used, then reciprocating motion is achieved, but the empty weight of the hand-held tool increases
Solution Approach 1:
By segmenting the motion converter into minimal essential components, the total mass of moving parts is reduced. The eccentric element, guide element, and pendulum element together weigh significantly less than the multiple connecting rods and linkages of conventional designs.
Solution Approach 2:
The patent changes the fundamental motion parameters by using an eccentric element that directly generates elliptical motion from rotational input, eliminating the need for complex mechanical advantage linkages. This parameter change in the motion generation approach reduces the mass of required components.
3Productivity
If conventional eccentric drives with multiple connecting rods are used, then motion conversion is achieved, but the structure becomes costly to manufacture
Solution Approach 1:
The motion converter is segmented into three simple, manufacturable components that can be produced using standard machining processes. The eccentric element, guide element, and pendulum element are each simple geometric forms that are cost-effective to manufacture compared to complex linkage assemblies.
Solution Approach 2:
The patent merges the functions of multiple conventional components into a single integrated pendulum element that combines the motion conversion and transmission functions, reducing the total number of parts and assembly steps, thereby lowering manufacturing costs.
4Power
If conventional motion converters are used, then reciprocating motion is generated, but energy efficiency is reduced due to friction and complexity
Solution Approach 1:
The patent extracts and removes unnecessary intermediate linkages that introduce friction and energy losses. By using only the essential eccentric element, guide element, and pendulum element, the number of friction interfaces is minimized, improving energy efficiency.
Solution Approach 2:
The pendulum element acts as a counterweight that balances the inertial forces generated by the eccentric element, reducing vibrations and energy losses. This counterbalancing effect improves energy efficiency by minimizing unnecessary energy dissipation through vibrations and friction.
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 solution provides a robust, low-cost, and energy-efficient conversion of rotational motion into a lifting motion, enabling rapid and efficient sawing with high cutting power and reduced wear, suitable for various hand-held machine tools.
Implementation Method 1
an eccentric element driven by the output shaft rotationally about an axis of rotation with a driver part arranged eccentrically to the axis of rotation
Implementation Method 2
a pendulum element which is mounted pivotably about a bearing point and is connected via a coupling point to the spindle
Implementation Method 3
the guide element allows a motion component, directed along the first axis of the pendulum element, of the driver part relative to the pendulum element and largely prevents a motion component, directed perpendicular to the first axis of the pendulum element
Implementation Method 4
featuring a worm drive, needle bearing, and an eccentric counterweight for reduced friction and improved cutting efficiency
Implementation Method 5
featuring a worm drive
Implementation Method 6
an eccentric counterweight for reduced friction and improved cutting efficiency
Data Source
AI summary
There is a hand-held machine tool, in particular a saber saw, with a housing, a drive motor with an output shaft, a spindle for receiving a tool, in particular a saw blade, and a motion converter for converting a rotational motion of the drive shaft into a reciprocating motion of the spindle. The motion converter comprises an eccentric element driven by the output shaft rotationally about an axis of rotation with a driver part arranged eccentrically to the axis of rotation, and a pendulum element which is mounted pivotably about a bearing point and is connected via a coupling point to the spindle. The pendulum element has a guide element for guiding the driver part. In one embodiment, the guide element is arranged between the bearing point and coupling point.