Electronically commutated DC motor with shielding

Patent metadata

Field	Value
Publication number	US-9673686-B2
Application number	US-201314401865-A
Country	US
Kind code	B2
Filing date	Apr 29, 2013
Priority date	May 25, 2012
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

In an electronically commutated DC motor having a stator unit ( 5 ) and a rotor unit ( 1 ) which is in the form of an external rotor, and having stationary sintered bearings ( 8, 9 ), the invention proposes that the rotor unit ( 1 ) is conductively connected to the shaft ( 3 ) in order to connect a conductive shielding, which is formed on the rotor unit ( 1 ), to a defined electrical potential, and that the sintered bearing ( 8, 9 ) is conductively connected to the potential, so that the shielding of the rotor unit ( 1 ) is capacitively coupled to the potential by means of the electrically insulating, oil-filled bearing gap which is arranged between the shaft ( 3 ) and the sintered bearing ( 8, 9 ). Therefore, a sliding contact is not required.

First claim

What is claimed is:

1. A DC motor, comprising a stator unit ( 5 ) and a rotor unit ( 1 ) which is connected to an electrically conductive shaft ( 3 ) in a rotationally fixed manner, said shaft being rotatably mounted in at least one stationary sintered bearing ( 8 , 9 ), characterized in that a shielding of the rotor unit ( 1 ) is conductively connected to the shaft ( 3 ) in order to connect a conductive shielding, which is formed on the rotor unit ( 1 ), to a defined electrical potential and in that the sintered bearing ( 8 , 9 ) is conductively connected to the potential, so that the shielding of the rotor unit ( 1 ) is capacitively coupled to the potential by means of an at least partially electrically insulating, oil-filled bearing gap which is arranged between the shaft ( 3 ) and the sintered bearing ( 8 , 9 ), wherein current is discharged from the shielding of the rotor unit ( 1 ) to the potential via the at least partially insulating, oil-filled bearing gap.

2. The DC motor according to claim 1 , characterized in that the rotor unit ( 1 ) comprises a pot-shaped metallic pole housing which forms the shielding of the rotor unit.

3. The DC motor according to claim 1 , characterized in that the shaft ( 3 ) is rotatably mounted in a first sintered bearing ( 8 ) and a second sintered bearing ( 9 ) which are axially spaced apart from one another and are in each case conductively connected to the defined potential, providing two parallel capacitive couplings of the shaft ( 3 ) to the potential.

4. The DC motor according to claim 1 , characterized in that a metal plate ( 13 ) connected to the defined potential is provided for additional shielding of the motor in an axial direction that is opposite the shielding of the rotor unit ( 1 ), said metal plate being disposed on an end face of the stator unit ( 5 ) that faces away from the rotor unit ( 1 ) and being conductively connected to at least one sintered bearing ( 8 , 9 ) via a connection means ( 14 , 15 , 16 , 17 ).

5. The DC motor according to claim 4 , characterized in that a first sintered bearing ( 8 ) is disposed in a region of an end face of the stator unit ( 5 ) that faces the rotor unit ( 1 ) and in that the connection means ( 14 , 15 , 16 , 17 ) comprises a pin ( 14 ).

6. The DC motor according to claim 5 , characterized in that the pin ( 14 ) is encased with a dome-shaped plastic overmold to a point in close proximity to a free end of the pin.

7. The DC motor according to claim 5 , characterized in that the connection means comprises a first contact spring ( 15 ) which is arranged axially and abuts resiliently against the first sintered bearing ( 8 ).

8. The DC motor according to claim 7 , characterized in that a second contact spring ( 16 ) which extends in the axial direction is connected in an electrically conductive manner to an end of the first contact spring ( 15 ) that faces away from the rotor unit ( 1 ), said second contact spring abutting resiliently against the second sintered bearing ( 9 ).

9. The DC motor according to claim 7 , characterized in that an end of the pin ( 14 ) which faces the rotor unit ( 1 ) and an end of the first contact spring ( 15 ) are connected electrically to one another by means of a litz wire ( 17 ).

10. The DC motor according to claim 4 , characterized in that a first sintered bearing ( 8 ) is disposed in a region of an end face of the stator unit ( 5 ) that faces the rotor unit ( 1 ) and in that the connection means ( 14 , 15 , 16 , 17 ) comprises a pin ( 14 ) which is integrally connected to the metal plate ( 13 ) and extends in the axial direction from the metal plate ( 13 ) through the stator unit ( 5 ) up into the region of the end face thereof that faces the rotor unit ( 1 ).

11. The DC motor according to claim 10 , characterized in that the pin ( 14 ) is encased with a dome-shaped plastic overmold to a point in close proximity to a free end of the pin.

12. The DC motor according to claim 10 , characterized in that the connection means comprises a first contact spring ( 15 ) which is arranged axially and abuts resiliently against an electrically conductive first clamping collar ( 10 ) which presses the first bearing ( 8 ) into a seat thereof.

13. The DC motor according to claim 12 , characterized in that a second contact spring ( 16 ) which extends in the axial direction is connected in an electrically conductive manner to an end of the first contact spring ( 15 ) that faces away from the rotor unit ( 1 ), said second contact spring abutting resiliently against an electrically conductive second clamping collar ( 11 ) which presses the second bearing ( 9 ) into a seat thereof.

14. The DC motor according to claim 1 , characterized in that a fan wheel ( 2 ) is fastened to the shaft ( 3 ) in a rotationally fixed manner outside of the rotor unit ( 1 ) and in that the DC motor is a fan motor comprising integrated commutating electronics.

15. The DC motor according to claim 1 , wherein the current is provided by high-frequency interference generated by the motor.

Assignees

• Bosch Gmbh Robert

Inventors

• Rothfuss Tobias
• Maelzer Michael
• Munz Juergen
• Hermann Michael
• Prahl Detlef
• Schoser Siegmar
• Brandes Joerg
• Schiel Andreas
• Banky Tamas
• Dudas Zsolt

Classifications

• H02K11/01

  for shielding from electromagnetic fields {, i.e. structural association with shields} (means for preventing or reducing eddy-current losses in the winding heads by shielding H02K3/42) · CPC title

• H02K11/40

  Structural association with grounding devices · CPC title

• H02K5/16

  Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields (magnetic bearings H02K7/09) · CPC title

• H02K11/022 Primary

  Electricity · mapped topic

• H02K11/0141 Primary

  Shields associated with casings, enclosures or brackets · CPC title