Saw Drivetrain Layout for Right Bevel Cuts and Low Profile

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Solution Overview

Problem

Conventional miter saws are limited in their ability to perform left and right bevel cuts due to the motor and drivetrain configuration, which is bulky, heavy, and causes power losses, and increases the vertical size of the saw, interfering with user operation and visibility.

Innovation Solution

A compact drivetrain arrangement using a gear train and chain drive system where the motor output shaft and intermediate shaft are aligned vertically with the arbor shaft, with the motor housed entirely below the horizontal plane, allowing for efficient transmission of power and reduced interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the motor and drivetrain are positioned on the right side of the miter saw, then the saw can perform crosscuts and left bevel cuts, but the motor and drivetrain interfere with right bevel angle settings

Engineering Contradiction:
Improvebevel cut capabilityVSAvoidright bevel adjustment
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The motor is repositioned from a horizontal arrangement (right side of the saw) to a vertical arrangement (above the blade guard), utilizing the vertical dimension to resolve the spatial conflict between motor placement and right bevel operation

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If the motor is moved above the blade guard to enable right bevel cuts, then right bevel angle settings become possible, but the drivetrain becomes bulky and heavy requiring many gears

Engineering Contradiction:
Improveright bevel cut capabilityVSAvoiddrivetrain gear count
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces a complex multi-gear drivetrain system with a simplified direct-drive or reduced-gear drivetrain, substituting mechanical complexity with an alternative transmission approach that achieves the same function with fewer components

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If the motor is positioned above the blade guard, then right bevel cuts are enabled, but power losses occur due to friction in the belt or gear transmission

Engineering Contradiction:
Improveright bevel cut capabilityVSAvoidpower transmission loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent eliminates friction-based belt or gear transmission by using a direct-drive configuration where the motor shaft is directly coupled to the arbor shaft, substituting the mechanical transmission system with a direct connection that eliminates transmission losses

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Adaptability or versatility

If the drivetrain extends above the upper blade guard, then the motor can be positioned for right bevel cuts, but the vertical size of the saw increases

Engineering Contradiction:
Improveright bevel cut capabilityVSAvoidsaw vertical height
Core Design Contradiction:
Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The patent repositions the motor and drivetrain components within the vertical dimension (below the blade guard level) rather than extending above it, utilizing downward orientation to achieve right bevel capability without increasing the saw's upward profile

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

Enables the saw to perform left and right bevel cuts with reduced motor interference, minimizing power losses and maintaining a compact vertical profile, enhancing user accessibility and operational ease.

Implementation Method 1

a gear train including a first gear fixedly connected to the motor output shaft and a second gear fixedly connected to an intermediate shaft, the first gear meshing with the second gear so as to transmit rotation from the motor output shaft to the second gear

Methodology Applied
Scientific EffectGear: Gear

Implementation Method 2

The chain drive has a driving sprocket fixedly connected to the intermediate shaft, a driven sprocket, and a chain configured to transmit rotation of the driving sprocket to rotation of the driven sprocket

Methodology Applied
Scientific EffectChain: Chain

Data Source

PatentEP3797912A1Saw drivetrain with a chain drive and gear train
Publication Date: 2021.03.31 ROBERT BOSCH GMBH
  • EP3797912A1 patent drawingFigure 1
  • EP3797912A1 patent drawingFigure 2
  • EP3797912A1 patent drawingFigure 3

AI summary

A saw device (100) includes a motor (184) having a motor output shaft (212) and a drivetrain (188) that includes a gear train (220) and a chain drive (240). The gear train (220) has a first gear (224) fixedly connected to the motor output shaft (212) and a second gear (228) fixedly connected to an intermediate shaft (232), the first gear (224) meshing with the second gear (228) so as to transmit rotation from the motor output shaft (212) to the second gear (228). The chain drive (240) has a driving sprocket (244) fixedly connected to the intermediate shaft (232), a driven sprocket (252), and a chain (248) configured to transmit rotation of the driving sprocket (244) to rotation of the driven sprocket (252). The saw device (100) further includes an arbor shaft (260) fixedly connected to the driven sprocket (252), the arbor shaft (260) configured to mount a saw blade (102) such that the saw blade (102) rotates with the arbor shaft (260), and an upper guard (192) configured to enclose at least a portion of the saw blade (102).