Patent ID: 7270320
Filing Date: 2007-09-18
Classification: B27B,F16F

Abstract:
1. A portable handheld work apparatus comprising: a first housing part; a drive motor connected to said first housing part; a second housing part and a handle connected to said second housing part; an antivibration unit subject to deformation under load during operation of said work apparatus; said antivibration unit having a spring constant which increases in response to said load and said deformation thereby facilitating a good guidance of said work apparatus when held and used by an operator; said antivibration unit including: a coil spring defining a longitudinal axis and having an end section, a mid section and a transition section extending from said end section to said mid section; said coil spring having a first end fixed to said first housing part and having a second end fixed to said second housing part so as to cause said first housing part to be connected to said second housing part via said coil spring; a guide member having a helically-shaped guide slot wherein turns of said coil spring are guided; said end section and said transition section being guided in said helically-shaped guide slot; said end section being fixed in said helically-shaped guide slot so that said coil spring is fixed to said first housing part via said helically-shaped guide slot; said guide slot having first and second flanks delimiting said slot in the direction of said longitudinal axis; said transition section having a first play (c) to said first flank in the direction of said axis and a second play (d) to said second flank; said helically-shaped guide slot having a base and said transition section being guided on said guide slot with a third play (b) to said base in radial direction so as to cause the turns of said transition section to be moveable in said radial direction relative to said helically-shaped slot in the unloaded state of said antivibration unit and contribute to the spring action of said antivibration unit; and, wherein said third play (b), which is present in radial direction, is overcome during the deformation of said coil spring under load in a direction perpendicular to said longitudinal axis and the turns of said transition section come at least in part into contact engagement with said helically-shaped slot so that the spring stiffness of said antivibration unit increases because of said at least in part contact engagement of the turns of said transition section.