Portable handheld work apparatus having an internal combustion engine

Patent metadata

Field	Value
Publication number	US-9016246-B2
Application number	US-201213458756-A
Country	US
Kind code	B2
Filing date	Apr 27, 2012
Priority date	Feb 9, 2009
Publication date	Apr 28, 2015
Grant date	Apr 28, 2015

Abstract

In an internal combustion engine ( 2 ) of a portable handheld work apparatus, the cylinder ( 3 ) is provided with cooling ribs ( 4, 4′ ). A cooling airflow is generated by the fan wheel ( 13 ) and is guided over the cooling ribs. A carburetor ( 9 ) is temperaturized as required by the heated cooling air. A control of the cooling airflow to the carburetor ( 9 ) takes place in that an opening ( 11 ), which passes the heated cooling air, is selectively closed or opened via a closure element ( 12 ). In order to obtain improved cooling of the cylinder during summer operation as well as during winter operation, the closure element ( 12 ) is provided with at least one air guide wall which extends essentially transversely to the cooling airflow and causes this cooling air to be partially backed up and deflected.

First claim

What is claimed is:

1. A portable handheld work apparatus comprising:
an internal combustion engine having a cylinder provided with cooling ribs;
a carburetor having a carburetor housing and being operatively connected to said engine;
a fan wheel for generating a cooling airflow passing over said cooling ribs causing said cooling airflow to become a heated cooling airflow;
a housing having an engine compartment for accommodating said engine therein and a carburetor compartment for accommodating said carburetor therein and having an intermediate wall separating said compartments from each other;
an opening passing said heated cooling airflow to said carburetor for temperaturizing said carburetor as may be needed;
a closure element for selectively opening or closing said opening for controlling the heated cooling airflow to said carburetor;
said opening being disposed in said intermediate wall;
said closure element having an air guide wall extending substantially transversely to said heated cooling airflow so as to cause said heated cooling airflow to be at least in part backed up and deflected; and,
said closure element being configured to be in a selectable position so as to cause said heated cooling airflow to be split into a first component of heated cooling airflow configured to flow into said carburetor compartment to there flow about said carburetor housing so as to warm said carburetor housing from the outside thereof and a second component of heated cooling airflow configured to flow toward said cooling ribs.

2. The portable handheld work apparatus of claim 1 , wherein said closure element is configured as an insert component.

3. The portable handheld work apparatus of claim 2 , wherein said insert component is elongated and has a mid section for selectively closing said opening; and, said insert component further has first and second insert sections for attaching said insert component.

4. The portable handheld work apparatus of claim 3 , further comprising receiving fixtures close to said opening into which said insert component can be inserted.

5. The portable handheld work apparatus of claim 4 , wherein each of said receiving fixtures defines a slot for accommodating a corresponding one of said insert sections therein.

6. The portable handheld work apparatus of claim 2 , wherein said insert component has at least one latch projection; and, wherein said apparatus further comprises a latch hook on said intermediate wall for coacting with said latch projection.

7. The portable handheld work apparatus of claim 3 , wherein said insert component has a longitudinal side and an air guide wall on said longitudinal side which extends substantially over the length of said insert component.

8. The portable handheld work apparatus of claim 3 , wherein said insert component is selectably mountable with respect to said opening in one of two positions; said insert component has a longitudinal side and a channel on said longitudinal side for conducting said first component heated cooling airflow to said carburetor; and, said channel is in overlapment with said opening in one of said two positions.

9. The portable handheld work apparatus of claim 8 , wherein said longitudinal side of said insert component is a first longitudinal side and said insert component has a second longitudinal side next to said channel; and, said insert component further has a short air guide wall arranged next to said channel.

10. A portable handheld work apparatus comprising:
a housing having an intermediate wall partitioning said housing into an engine compartment and a carburetor compartment;
an internal combustion engine mounted in said engine compartment and having a cylinder provided with cooling ribs;
a carburetor operatively mounted in said carburator compartment and being connected to said engine;
said carburetor having a carburetor housing;
a fan wheel for generating a cooling airflow passing over said cooling ribs causing said cooling airflow to become a heated cooling airflow;
an opening formed in said intermediate wall for passing said heated cooling airflow to said carburetor for temperaturizing said carburetor as may be needed;
a closure element for selectively opening or closing said opening for controlling the heated cooling airflow to said carburetor;
said closure element being mounted on said intermediate wall in said en sine compartment;
said closure element having an air guide wall extending substantially transversely to said heated cooling airflow so as to cause said heated cooling airflow to be at least in part backed up and deflected;
said closure element being configured to be in a selectable position so as to cause said heated cooling airflow to be split into a first component of heated cooling airflow to said carburetor to there flow about said carburetor housing so as to warm said carburetor housing from the outside thereof and a second component of heated cooling airflow toward said cooling ribs;
said closure element including a first part in the form of a fixed socket and a second part in the form of a movable slider;
said socket having a channel formed therein which can be cleared or blocked by said slider; and,
said channel being configured to be at least partially disposed in said cooling air flow when said channel is cleared.

11. The portable handheld work apparatus of claim 10 , wherein said slider is limitedly linearly movable on said socket.

12. The portable handheld work apparatus of claim 10 wherein said slider has a blocking section formed thereon via which said channel can be closed.

13. The portable handheld work apparatus of claim 10 , wherein said socket has attachment hooks and lateral rails arranged thereon for attaching said socket to said intermediate wall.

14. The portable handheld work apparatus of claim 10 , wherein said slider has a handle for shifting said slider.

15. The portable handheld work apparatus of claim 10 , wherein said socket is said air guide wall and said slider only has the function to block said channel or to clear said channel.

16. The portable handheld work apparatus of claim 10 , wherein said socket has two elongated recesses with which said slider can be held in defined positions.

17. The portable handheld work apparatus of claim 10 , wherein said socket and said slider are each made of plastic.

18. The portable handheld work apparatus of claim 1 , wherein said carburetor is arranged in said carburetor compartment; and, said carburetor compartment is configured to enable said heated cooling airflow to circulate freely therein.

19. A portable handheld work apparatus comprising:
an internal combustion engine having a cylinder provided with cooling ribs;
a carburetor having a carburator housing and being operatively connected to said engine;
a fan wheel for generating a cooling airflow passing over said cooling ribs causing said cooling airflow to become a heated cooling airflow;
an opening configured to pass said heated cooling airflow to said carburetor for temperaturizing said carburetor as may be needed;
a closure element for selectively opening or closing said opening for controlling the heated cooling airflow to said carburetor;
said closure element having an air guide wall extending substantially transversely to said heated cooling airflow so as cause said heated cooling airflow to be at least in part backed up and deflected; and,
said closure element being configured to be in a selectable position so as to cause said heated cooling airflow to be split into a firs

Assignees

• Kurzenberger Jan
• Hecht Thorsten
• Hänssler Sebastian
• Kummermehr Stefan
• Stihl Ag & Co Kg Andreas

Inventors

• Kurzenberger Jan
• Hecht Thorsten
• Hänssler Sebastian
• Kummermehr Stefan

Classifications

• F02M35/1019

  Two-stroke engines; Reverse-flow scavenged or cross scavenged engines · CPC title

• F02F1/30

  Finned cylinder heads · CPC title

• F02F1/34

  with means for directing or distributing cooling medium · CPC title

• F02B63/02

  for hand-held tools · CPC title

• F01P1/02

  Arrangements for cooling cylinders or cylinder heads, e.g. ducting cooling-air from its pressure source to cylinders or along cylinders · CPC title