Work apparatus

Patent metadata

Field	Value
Publication number	US-9379596-B2
Application number	US-201313859144-A
Country	US
Kind code	B2
Filing date	Apr 9, 2013
Priority date	Apr 16, 2012
Publication date	Jun 28, 2016
Grant date	Jun 28, 2016

Abstract

A work apparatus has a tool which is driven in rotation by a drive motor via a transmission. The drive motor is an electric motor which has a commutator and brushes. The drive motor is arranged in a motor housing and drives an impeller wheel which conveys a cooling airflow for the drive motor. Simple and effective lubrication of the transmission is achieved with the cooling airflow flowing past the commutator and brushes and the transmission is arranged downstream of the commutator in the cooling airflow. The motor housing is formed in a manner closed toward the transmission housing on that end side that faces the transmission housing and is connected to the transmission housing via a flow connection.

First claim

What is claimed is:

1. A work apparatus comprising:
a work tool;
a transmission;
an electric drive motor for rotatably driving said work tool via said transmission;
a motor housing defining a flow path for conducting a cooling airflow therealong and a motor housing interior;
said drive motor being mounted in said motor housing and having a coil and a commutator assembly including a commutator and brushes;
a fan wheel driven by said drive motor and said fan wheel being configured to move said cooling airflow over said coil and said commutator assembly during operation;
said motor housing having an end face and an exit opening for passing said cooling airflow out from said motor housing;
said exit opening being arranged in said flow path downstream of said commutator assembly;
a transmission housing defining a transmission housing interior;
said electric drive motor having a drive shaft projecting out of said motor housing at said end face;
said motor housing having a wall arranged at said end face separating said motor housing interior from said transmission housing interior;
said motor housing being configured to be closed off toward said transmission housing at said end face;
a flow connection connecting said motor housing to said transmission housing and configured to conduct at least a portion of said cooling airflow into said transmission housing; and,
said transmission being arranged in said cooling airflow through said transmission housing.

2. The work apparatus of claim 1 , wherein said cooling airflow transports carbon dust of said brushes to said transmission.

3. The work apparatus of claim 1 , wherein said transmission includes a plurality of meshing toothed gearwheels;
and, at least one of said toothed gearwheels is arranged in said cooling airflow through said transmission housing.

4. The work apparatus of claim 1 , wherein said cooling airflow passes first over said coil and then over said commutator assembly.

5. The work apparatus of claim 4 , wherein said cooling airflow flows from said coil to said commutator assembly in a first flow direction and flows in a second flow direction in said flow connection in a direction opposite to said first flow direction.

6. The work apparatus of claim 1 , wherein said drive motor defines a rotational axis; said drive motor further defines a first imaginary plane disposed at an end of said commutator assembly facing toward said transmission housing and said first imaginary plane extends perpendicular to said rotational axis; said first imaginary plane has a side facing away from said transmission housing; and, said exit opening is arranged on said side of said first imaginary plane.

7. The work apparatus of claim 1 , wherein said drive motor defines a rotation axis; said drive motor further defines a second imaginary plane at an end of said commutator assembly facing away from said transmission housing and said second imaginary plane extends perpendicular to said rotation axis; said second imaginary plane has a side facing away from said transmission housing; and, said exit opening is arranged on said side of said second imaginary plane.

8. The work apparatus of claim 1 , wherein said flow connection is configured as a connecting channel.

9. The work apparatus of claim 8 , wherein said connecting channel has an average length (L) which is at least approximately 5 cm.

10. The work apparatus of claim 1 , wherein said coil has an end facing away from said commutator assembly; and, said transmission is arranged at said end of said coil.

11. The work apparatus of claim 1 , wherein said transmission includes at least two mutually intermeshed toothed gearwheels having teeth made of plastic.

12. The work apparatus of claim 1 , wherein said fan wheel and said transmission are arranged on mutually opposite ends of said drive motor.

13. The work apparatus of claim 1 , wherein said fan wheel is arranged adjacent to said exit opening.

14. The work apparatus of claim 1 , wherein said fan wheel is arranged at least partially in said connecting channel.

15. The work apparatus of claim 8 , wherein said work apparatus further comprises an apparatus housing including at least two half shells; and, said motor housing, said transmission housing and said connecting channel are conjointly formed by said half shells.

16. The work apparatus of claim 1 , wherein said motor housing has at least one inlet opening and said transmission housing has at least one outlet opening; said flow connection is configured so as to cause said cooling airflow to enter said motor housing via said inlet opening and to exit from said transmission housing through said outlet opening, said outlet opening of said transmission housing is formed between the rotating work tool and said transmission housing; and, said outlet opening is at least partially delimited by said work tool.

17. The work apparatus of claim 16 , wherein said fan wheel is a first fan wheel and said work apparatus further comprises a second fan wheel; said work tool has an end facing toward said transmission housing; and, said second fan wheel is arranged at said end of said work tool.

18. The work apparatus of claim 1 , further comprising a handle housing and a shaft connecting said motor housing to said handle housing.

19. The work apparatus of claim 18 , wherein said handle housing has at least one air entry opening for cooling air; and, said shaft has an end segment arranged in said handle housing and said end segment has an outer circumference wherein shaft openings are formed for conducting said cooling air drawn in through said entry opening and said shaft openings into said shaft and into said motor housing.

20. The work apparatus of claim 18 , wherein said shaft is held so as to be displaceable in said handle housing; said work apparatus further comprises a latching device wherewith said shaft can be fixed in at least two positions relative to said handle housing; and, said latching device coacts with at least one of said shaft openings.

21. A work apparatus comprising:
a work tool;
a transmission;
an electric drive motor for rotatably driving said work tool via said transmission;
a housing having a motor housing and a transmission housing formed therein;
said motor housing defining a flow path for conducting a cooling airflow therealong;
said drive motor being mounted in said motor housing and having a coil and a commutator assembly including a commutator and brushes;
a fan wheel driven by said drive motor and said fan wheel being configured to move said cooling airflow over said coil and said commutator assembly during operation;
said motor housing having an end face and an exit opening for passing said cooling airflow out from said motor housing;
said exit opening being arranged in said flow path downstream of said commutator assembly;
said transmission housing being formed separately from said motor housing;
a transfer channel connecting said transmission housing to said motor housing;
said electric drive motor having a drive shaft projecting out of said motor housing at said end face thereof;
said motor housing having a wall arranged at said end face separating said motor housing from said transmission housing;
said motor housing being configured to be closed off toward said transmission housing at said end face;
said transfer channel being configured to conduct at least a portion of said cooling airflow into said transmission housing; and,
said transmission being arranged in sa

Assignees

• Stihl Ag & Co Kg Andreas

Inventors

• Kraetzig David

Classifications

• H02K7/145

  Hand-held machine tool · CPC title

• H02K9/06

  with fans or impellers driven by the machine shaft · CPC title

• A01D34/90 Primary

  for carrying by the operator · CPC title

• H02K9/28 Primary

  Cooling of commutators, slip-rings or brushes e.g. by ventilating · CPC title