Starter device for an internal combustion engine and handheld work apparatus having an internal combustion engine and said starter device

Patent metadata

Field	Value
Publication number	US-10309362-B2
Application number	US-201615011258-A
Country	US
Kind code	B2
Filing date	Jan 29, 2016
Priority date	Jan 29, 2015
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

A starter device for an internal combustion engine has an entrainer for coupling to the engine. The entrainer and an actuator of the starter device are mounted rotatably about a rotational axis. A damper spring is arranged between and operatively connects the entrainer and the actuator to each other. The starter device has at least one stud, on whose outer periphery the damper spring is mounted. The damper spring is a hinge spring wound from a spring wire. The cross section of the spring wire is rounded on the inner side of the spring wire. At least a portion of the cross section runs linearly on the outer side of the spring wire.

First claim

What is claimed is:

1. A starter device for an internal combustion engine having a crankshaft and defining a rotational axis, the starter device comprising:
an actuator configured to permit rotation to be imparted thereto to start said engine;
an entrainer having at least one coupling unit for coupling to said crankshaft of said engine;
said entrainer and said actuator being rotatably mounted about said rotational axis;
a damper spring arranged between and operatively connecting said entrainer and said actuator to each other;
at least one stud having an outer periphery;
said damper spring being mounted on said outer periphery of said stud;
said damper spring being a hinge spring wound from spring wire and said spring wire being wound to include a plurality of turns;
said damper spring being tensioned when starting said internal combustion engine whereupon said damper spring becomes tight onto said stud;
said damper spring defining a section plane containing said rotational axis;
said spring wire having a cross section in said section plane;
in said cross section, said spring wire having an axially measured width (e) and a radially measured thickness (d, g, h);
in said cross section, said spring wire further having a radially inner-lying inner side and a radially outer-lying outer side;
in said cross section, said inner side of said spring wire being a rounded inner side with said rounded inner side being in contact engagement with said outer periphery of said stud;
at least a portion of said cross section running linearly at said outer side of said spring wire; and,
said outer side of said spring wire lying exposed over at least half of said turns so as not to be in contact engagement with adjacent components.

2. The starter device of claim 1 , wherein said inner side of said spring wire runs in a through radius (r).

3. The starter device of claim 2 , wherein said radius (r) of said inner side is greater than half of said width (e).

4. The starter device of claim 1 , wherein said at least a portion of said cross section extends over at least 30% of said width (e).

5. The starter device of claim 1 , wherein said spring wire has transverse sides running transversely to said rotational axis and said at least a portion of said cross section runs linearly at said transverse sides.

6. The starter device of claim 5 , wherein said spring wire has respective transitions whereat said outer side runs into corresponding ones of said transverse sides with a radius (s, t).

7. The starter device of claim 6 , wherein said radius (s, t) of said transitions is less than one quarter of said width (e) of said spring wire.

8. The starter device of claim 1 , wherein said thickness (d, g, h) is at least as large as said width (e) of said spring wire.

9. The starter device of claim 1 , wherein said stud is a first stud configured to be part of said actuator; and, said starter device further comprises a second stud configured to be part of said entrainer and said second stud has an outer periphery; and, said actuator and said entrainer are mounted so as to cause the respective outer peripheries thereof to conjointly accommodate said damper spring thereon.

10. The starter device of claim 1 , wherein said damper spring defines an essentially constant turns diameter (f).

11. The starter device of claim 1 , wherein said damper spring has first and second end segments bent over inwardly; and, said damper spring is held on said actuator with said first end segment and held on said entrainer with said second end segment.

12. The starter device of claim 1 , wherein said at least one of said studs has depressions formed in the outer periphery thereof.

13. The starter device of claim 1 , wherein said coupling unit includes at least one pawl pivotally mounted on said entrainer and a cam contour fixedly mounted on said crankshaft so as to rotate therewith; and, said pawl and said cam contour are configured to coact to couple said starter device to said crankshaft.

14. The starter device of claim 1 , wherein said actuator is a rope pulley which is configured so as to permit rotation to be manually imparted thereto with a pull rope.

15. A handheld work apparatus comprising:
an internal combustion engine having a crankshaft and defining a rotational axis;
a starter device for said engine;
said starter device including: an actuator configured to permit rotation to be imparted thereto to start said engine; and, an entrainer having at least one coupling unit for coupling to said crankshaft of said engine;
said entrainer and said actuator being rotatably mounted about said rotational axis;
a damper spring arranged between and operatively connecting said entrainer and said actuator to each other;
said starter device further including at least one stud having an outer periphery;
said damper spring being mounted on said outer periphery of said stud;
said damper spring being a hinge spring wound from spring wire;
said damper spring defining a section plane containing said rotational axis;
said spring wire having a cross section in said section plane;
in said cross section, said spring wire having an axially measured width (e) and a radially measured thickness (d, g, h);
in said cross section, said spring wire further having a radially inner-lying inner side and a radially outer-lying outer side;
in said cross section, said inner side of said spring wire being a rounded inner side; and,
at least a portion of said cross section running linearly at said outer side of said spring wire.

16. A starter device for an internal combustion engine having a crankshaft and defining a rotational axis, the starter device comprising:
an actuator configured to permit rotation to be imparted thereto to start said engine;
an entrainer having at least one coupling unit for coupling to said crankshaft of said engine;
said entrainer and said actuator being rotatably mounted about said rotational axis;
a damper spring arranged between and operatively connecting said entrainer and said actuator to each other;
at least one stud having an outer periphery;
said damper spring being mounted on said outer periphery of said stud;
said damper spring being a hinge spring wound from spring wire and said spring wire being wound to include a plurality of turns;
said damper spring defining a section plane containing said rotational axis;
said spring wire having a cross section in said section plane;
in said section plane, said spring wire having an axially measured width (e) and a radially measured thickness (d, g, h);
in said cross section, said spring wire further having a radially inner-lying inner side and a radially outer-lying outer side;
said damper spring being mounted between said entrainer and said actuator so as to cause the outer diameter of said damper spring to be reduced when said actuator is actuated by an operator with said outer-lying outer side of said spring wire being exposed over at least half of said turns and lying at a spacing away from adjacent components;
in said cross section, said inner side of said spring wire being a rounded inner side; and,
at least a portion of said cross section running linearly at said outer side of said spring wire.

Assignees

• Stihl Ag & Co Kg Andreas

Inventors

• Behringer Patrick
• Keller Sven
• Vonderau Werner

Classifications

• F02B63/02

  for hand-held tools · CPC title

• F02N3/02 Primary

  having pull-cords · CPC title

• F02N5/02 Primary

  of spring type · CPC title

• F02B2075/025

  two · CPC title

• F02D2400/06

  Small engines with electronic control, e.g. for hand held tools · CPC title