Drive shaft in a handheld work apparatus

Patent metadata

Field	Value
Publication number	US-10670070-B2
Application number	US-201715795080-A
Country	US
Kind code	B2
Filing date	Oct 26, 2017
Priority date	Oct 31, 2016
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

A telescopic drive shaft in a protective tube of a handheld work apparatus has one end connected to a rotational drive and the other end thereof to a driven tool. The drive shaft includes a rigid shaft segment and a connecting section. The rigid shaft segment has a hollow shaft end portion and an engagement length (E) of the connecting section engages therein. The engagement length (E) and the length of the hollow shaft end portion mutually overlap to form a joining section. The hollow shaft end portion is deformed for connecting the connecting section to the rigid shaft segment. The material of the hollow shaft end portion is compressed over its entire periphery and deformed so that the material of the hollow shaft end portion is radially displaced and is pressed in a rotative manner onto the engagement length (E) to produce a balanced, loadable connection.

First claim

What is claimed is:

1. A drive shaft in a protective tube of a portable handheld work apparatus wherein a rotational drive is connected to a first end of the drive shaft and a work tool is connected to a second end of the drive shaft so as to be driven thereby, the drive shaft comprising:
at least one rigid shaft segment and at least one connecting section for transmitting torque;
said rigid shaft segment being configured to have at least one hollow shaft end portion;
said connecting section defining an engagement length (E) engaging into said hollow shaft end portion over a length thereof so as to cause said engagement length (E) and said length of said hollow shaft end portion to mutually overlap to conjointly define a joining section;
said joining section being configured by said hollow shaft end portion being deformed;
said hollow shaft end portion being made of a material which is compressed over the entire periphery thereof so as to cause said material to be radially displaced and pressed onto said engagement length (E) to form a rotative connection between said hollow shaft end portion and said engagement length (E); and,
said material of said hollow shaft end portion being circularly deformed over a periphery of 360° thereof while reducing the outer diameter (D 0 ) thereof.

2. The drive shaft of claim 1 , wherein said hollow shaft end portion is deformed over an axial length (V) thereof which is greater than said engagement length (E) of said connecting section.

3. The drive shaft of claim 1 , wherein at least said engagement length (E) of said connecting section has a peripheral surface with depressions formed therein; and, said material of said hollow shaft end portion is displaced into said depressions so as to engage therein.

4. The drive shaft of claim 1 , wherein the deformation of said material is performed with rotary swaging with press jaws acting on the periphery of said hollow shaft end portion while said press jaws and said hollow shaft end portion rotate relative to each other.

5. The drive shaft of claim 1 , wherein said connecting section is a flexible shaft section.

6. The drive shaft of claim 5 , wherein said flexible shaft section is a flex shaft.

7. The drive shaft of claim 5 , wherein said rigid shaft segment has an overall length (G); said flexible shaft section has a free length (L) outside of said hollow shaft end portion; and, said free length (L) lies in a range of 5% to 100% of said overall length (G).

8. The drive shaft of claim 5 , wherein said flexible shaft section is arranged at the end of said rigid shaft segment directed toward said rotational drive.

9. The drive shaft of claim 1 , wherein said drive shaft is a telescopic drive shaft.

10. A drive shaft in a protective tube of a portable handheld work apparatus wherein a rotational drive is connected to a first end of the drive shaft and a work tool is connected to a second end of the drive shaft so as to be driven thereby, the drive shaft comprising:
at least one rigid shaft segment and at least one connecting section for transmitting torque;
said rigid shaft segment being configured to have at least one hollow shaft end portion;
said connecting section defining an engagement length (E) engaging into said hollow shaft end portion over a length thereof so as to cause said engagement length (E) and said length of said hollow shaft end portion to mutually overlap to conjointly define a joining section;
said joining section being configured by said hollow shaft end portion being deformed;
said hollow shaft end portion being made of a material which is compressed over the entire periphery thereof so as to cause said material to be radially displaced and pressed onto said engagement length (E) to form a rotative connection between said hollow shaft end portion and said engagement length (E);
said joining section having first and second subsections defining first and second degrees of deformation, respectively; and,
said first and second degrees of deformation being of respectively different magnitudes.

11. The drive shaft of claim 10 , wherein said first degree of deformation is less than said second degree of deformation.

12. The drive shaft of claim 10 , wherein said hollow shaft end portion has a free end and said second subsection has said second degree of deformation defining said free end.

13. The drive shaft of claim 10 , wherein the deformed joining section has an outer contour which is circularly round and has an outer diameter (D 1 , D 2 ) smaller than the outer diameter of said rigid shaft segment beyond said joining section.

14. A drive shaft in a protective tube of a portable handheld work apparatus wherein a rotational drive is connected to a first end of the drive shaft and a work tool is connected to a second end of the drive shaft so as to be driven thereby, the drive shaft comprising:
at least one rigid shaft segment and at least one connecting section for transmitting torque;
said rigid shaft segment being configured to have at least one hollow shaft end portion;
said connecting section defining an engagement length (E) engaging into said hollow shaft end portion over a length thereof so as to cause said engagement length (E) and said length of said hollow shaft end portion to mutually overlap to conjointly define a joining section;
said joining section being configured by said hollow shaft end portion being deformed;
said hollow shaft end portion being made of a material which is compressed over the entire periphery thereof so as to cause said material to be radially displaced and pressed onto said engagement length (E) to form a rotative connection between said hollow shaft end portion and said engagement length (E);
said connecting section being a flexible shaft section having a free length (L);
said flexible shaft section having respective ends and a polygonal cross section at said ends; and,
the end of said connecting section, which projects into said hollow shaft end portion, having more corners than the end on the free length (L) of said flexible shaft section.

Assignees

• Stihl Ag & Co Kg Andreas

Inventors

• Weissert Wolfgang
• Foehrenbach Jan
• Wolf Andreas
• Bareiss Christian
• Rieger Andreas
• Pelludat Simone

Classifications

• F16C2322/50

  Hand tools, workshop equipment or manipulators · CPC title

• F16C1/262

  End fittings; Attachment thereof to the sheathing or tube · CPC title

• Y10T403/49

  Member deformed in situ · CPC title

• F16C2310/00

  Agricultural machines · CPC title

• Y10T74/2045

  and sheath support, connector, or anchor · CPC title