Offset Spur Gear Counterweighting for Low-Vibration Reciprocating Tools
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Solution Overview
Problem
Reciprocating tools experience vibration due to acceleration/deceleration at extreme ends of travel, affecting user control, precision, and causing fatigue, especially at increased operational speeds and stroke lengths.
Innovation Solution
A reciprocating power tool with a transmission system featuring a gear shaft with offset spur gears driving both a reciprocating device and a counterbalancing mechanism, where the reciprocating directions are orthogonal and 180 degrees out of phase, using a pin and protrusion mechanism to convert rotational force into balanced linear motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If operational speed and stroke length are increased, then productivity is improved, but vibration increases causing user fatigue and reduced control
Solution Approach 1:
The patent applies counterweighting by adding a counterbalancing mechanism with a counterweight that moves in opposition to the reciprocating mechanism. This counterweight generates opposing inertial forces that cancel out the vibrations produced by the high-speed reciprocating motion, allowing increased operational speed and stroke length without proportionally increasing vibration and user fatigue
2Productivity
If a reciprocating mechanism is added to convert rotational force to linear motion, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent merges the drive train and counterbalancing mechanism into a single integrated transmission system. Both the reciprocating mechanism and counterbalancing mechanism share common components including the gear shaft, gears, and crankshaft, allowing the system to achieve linear motion conversion and vibration reduction simultaneously without proportionally increasing device complexity
3Productivity
If the reciprocating mechanism operates at higher speeds, then productivity is improved, but precision deteriorates due to vibration
Solution Approach 1:
The counterbalancing mechanism reduces vibrations that would otherwise degrade cutting precision at high speeds. By canceling out the oscillatory forces generated during high-speed reciprocating motion, the system maintains stable operation and precise cutting performance even at increased operational speeds
4Reliability
If a counterbalancing mechanism is added to reduce vibration, then reliability is improved, but device complexity increases
Solution Approach 1:
The counterbalancing mechanism is integrated with the existing drive train through shared components (gear shaft, gears, crankshaft). This merging approach allows the system to achieve vibration reduction and improved reliability while minimizing the increase in device complexity, as the counterbalancing function is achieved through clever arrangement of existing transmission elements rather than completely separate additional mechanisms
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 reduces vibration, enhancing precision, stability, and reducing operator fatigue by balancing the reciprocating forces, allowing for more precise and efficient tool operation.
Implementation Method 1
a transmission including a gear shaft configured to rotate in response to a driving force from the motor, the gear shaft including: a first gear portion formed on a first portion of the gear shaft, the first gear portion driving a first output gear, the first output gear driving the reciprocating device; and a second gear portion formed on a second portion of the gear shaft, the second gear portion driving a second output gear, the second output gear driving the counterbalancing device
Implementation Method 2
a pin fixed to the first output gear and coupled in a slot formed in a yoke portion of the reciprocating shaft, wherein the pin is eccentrically positioned relative to the second axis of rotation
Implementation Method 3
a linear reciprocating direction of the counterbalancing device is opposite a linear reciprocating direction of the reciprocating device so as to balance a linear reciprocating movement of the reciprocating device
Data Source
AI summary
A reciprocating power tool includes a transmission that converts rotational force from a motor to linear forces output by a reciprocating device and a counterbalancing device. The transmission is a parallel axis transmission including a first gear portion and a second gear portion formed on a gear shaft, with the first gear portion and the second gear portion rotating together about a first rotational axis. The first gear portion rotates a first output gear and the second gear portion rotates a second output gear about a second rotational axis that is parallel to and offset from the first rotational axis. The first output gear drives the reciprocating device and the second output gear drives the counterbalancing device. The reciprocating device reciprocates linearly and the counterbalancing devices performs a linear reciprocating movement that is opposite that of the reciprocating device to counterbalance forces generated by operation of the reciprocating device.