Saber Saw Guide Yoke Decoupling Rotary and Lifting Motion

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Solution Overview

Problem

Machine tools like jigsaws face challenges in achieving compact design with lifting and rotary capabilities while maintaining precise and stable guidance of the saw blade, as existing configurations result in play between guide links and undesired drive influences.

Innovation Solution

The use of a guide yoke supported on the housing, which allows the link body to be offset and decoupled from the saw blade, enabling rotation without affecting the lifting drive, and a pivot bolt for rotational mobility, along with a sliding guide for non-circular cross-sections, facilitates access and stable operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the guide link is integrated with the crank mechanism on the housing side, then the structure is compact, but play occurs between the guide link and crank pin, reducing guidance precision

Engineering Contradiction:
Improvestructural compactnessVSAvoidguidance precision
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent divides the guide system into separate components: the guide yoke (Lenker) and the crank mechanism are separated and independently supported on the housing. This segmentation eliminates the play between integrated parts while maintaining compact overall structure through independent mounting positions.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If the saw blade is directly guided by the crank mechanism, then the lifting drive is simple, but rotation of the saw blade creates undesired drive influences and repercussions on the lifting mechanism

Engineering Contradiction:
Improvelifting drive complexityVSAvoidlifting guide stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The guide yoke serves as an intermediary component between the crank mechanism and the saw blade. It is rotatably connected to the crank pin and guides the lifting rod, thereby mediating the rotational movements and preventing them from directly influencing the lifting drive mechanism.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The guide yoke is extracted as a separate, independently supported component from the crank mechanism. This allows the guide yoke to handle rotational guidance while the crank mechanism focuses solely on the lifting function, eliminating cross-influences between the two functions.

Inventive Principle:
Principle #2Taking out (Extraction)

3Volume of moving object

If the guide structure is integrated close to the saw blade, then the design is compact, but access for rotary adjustment of the working tool is limited

Engineering Contradiction:
Improvedesign compactnessVSAvoidaccess for rotary adjustment
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

The guide yoke is offset in level with the saw blade along the lifting direction, creating a spatial separation in the vertical dimension. This allows the rotary adjustment mechanism to access the guide yoke from the side or top, improving accessibility while maintaining compact horizontal footprint.

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

Data Source

PatentEP2490849B1Machine tool
Publication Date: 2013.05.29 ROBERT BOSCH GMBH
  • EP2490849B1 patent drawingFigure 1
  • EP2490849B1 patent drawingFigure 2
  • EP2490849B1 patent drawingFigure 3

AI summary

A machine tool (2) designed as a sabre saw (3) driven by an electric motor comprises a support of the saw blade (4) that can be rotated about the lifting axis (15) thereof against a guide yoke (17) guided in a slidable manner in the lifting direction, said yoke carrying the slot body (12) of a Scotch yoke drive mechanism (8) that comprises the guide slot (11), by means of which drive mechanism the lifting drive of the saw blade (4) is carried out.