Ultra quiet electric motor for automotive applications

• US 5,945,756 A
• Filed: 10/07/1997
• Issued: 08/31/1999
• Est. Priority Date: 10/07/1997
• Status: Expired due to Term

• Current Assignee: Brose Fahrzeugteile GmbH & Company KG Wã¼Rzburg
• Original Assignee: Siemens Canada Limited (Siemens AG)
• Inventors: Horski, Marek, Kershaw, Peter A., Periyathamby, Haran K.
• Primary Examiner(s): Ramirez, Nestor
• Assistant Examiner(s): Nguyen, Tran N
• Application Number:
  US08/946,481
• Time in Patent Office: 693 Days
• Field of Search: 310/43, 310/51, 310/90, 310/91, 310/89, 310/239, 310/242, 310/245, 310/248, 384/192, 384/195, 384/202, 384/203, 384/210, 384/204, 384/217, 384/220
• US Class Current: 310/89
• CPC Class Codes: H02K 5/143 for cooperation with commutators
• CPC Class Codes: H02K 5/1672 radially supporting the rotary shaft at both ends of the rotor H02K5/1677 takes precedence
• CPC Class Codes: H02K 5/24 specially adapted for suppression or reduction of noise or vibrations

Abstract

A high speed electric motor for automotive applications that is designed to effectively minimize vibration of its component parts and thus suppress noise generated during its operation. The motor incorporates acoustic engineering principles including surface vibration control, acoustic radiation efficiency, active intensity field control and noise control using acoustic materials to reduce overall vibration of the motor components and the motor noise sensed by the passenger of the vehicle.

Claims

1. An electric motor for automotive applications that exhibits minimal acoustic noise radiation, which comprises:

a housing having front and rear ends, and an internal chamber;

an armature shaft;

an end cap mounted adjacent the rear end of the housing to substantially enclose the internal chamber of the housing, the end cap comprising;

a hub extending radially outwardly with respect to a cylindrical section of said housing, and

a stamped pattern including a series of alternating axial raised portions and depression portions located in an inner peripheral surface of said hub;

a brush card assembly proximate the end cap, the brush card assembly including a brush card mount and a brush card supported by the brush card mount; and

at least one bearing assembly including;

a bearing member that supports an end portion of the armature shaft; and

a bearing housing having an internal bore defining a receiving wall portion to accommodate at least a portion of the bearing member, the bearing housing being dimensioned such that the receiving wall portion of the bearing housing is in contacting engagement with an outer surface of the bearing member to facilitate absorption of vibration energy from the bearing.

2. The electric motor according to claim 1 wherein the bearing housing comprises a vibration energy absorbing material.

3. The electric motor according to claim 1 wherein the end cap includes a main portion and a peripheral lip portion extending in an axial direction from the main portion, the main portion having the stamped pattern.

4. The electric motor according to claim 1 wherein the bearing housing includes a base defining a central axis, and a plurality of mounting projections extending from the base, the mounting projections configured to surround at least a portion of the bearing member to facilitate retention of the bearing member within the bearing housing.

5. The electric motor according to claim 4 wherein the mounting projections are dimensioned such that a gap is defined between the portion of the bearing member and the mounting projections to permit adjusting movement of the bearing member within the bearing housing.

6. The electric motor according to claim 5 including first and second bearing assemblies.

7. The electric motor according to claim 1 further including energy absorbing material at least partially surrounding the one bearing assembly to absorb residual acoustic energy.

8. The electric motor according to claim 1 further including a noise absorption member disposed adjacent the one bearing assembly to absorb noise energy emanating from the one bearing.

9. The electric motor according to claim 1 further including an anti-vibration washer mounted to the armature shaft adjacent the one bearing assembly configured to absorb vibration energy transferred along the armature shaft.

10. The electric motor according to claim 1 including at least one fastener extending through corresponding apertures of the end cap, the brush card mount and the housing, to operatively connect the end cap to the housing.

11. The electric motor according to claim 10 wherein the at least one fastener includes a substantially rigid spacer sleeve coaxially mounted thereabout, the spacer sleeve disposed between the end cap and the rear end of the housing to maintain a predetermined distance therebetween.

12. The electric motor according to claim 1 further including a motor mounting flange connected to the housing for mounting the housing to a vehicle frame, the mounting flange including a stamped pattern having a plurality of peripherally positioned depressed portions, the stamped pattern configured to absorb vibration energy.

13. The electric motor according to claim 1 wherein the housing is dimensioned to minimize noise energy, the housing defining a main body section and having an internal cross-sectional dimension, the main body section defining a length ranging from about 0.50 to about 0.80 times the distance of the internal dimension.

14. An electric motor for automotive applications that exhibits minimal acoustic noise radiation, which comprises:

a housing having front and rear ends, and an internal chamber;

an armature shaft;

an end cap mounted adjacent the rear end of the housing to substantially enclose the internal chamber of the housing, the end cap having a stamped pattern including at least one raised portion configured to minimize vibration energy transfer, the end cap including a main portion and a peripheral lip portion extending in an axial direction from the main portion, the main portion having the stamped pattern; and

a brush card assembly proximate the end cap, the brush card assembly including a brush card mount and a brush card supported by the brush card mount; and

at least one bearing assembly including;

a bearing member that supports an end portion of the armature shaft; and

a bearing housing having an internal bore defining a receiving wall portion to accommodate at least a portion of the bearing member, the bearing housing being dimensioned such that the receiving wall portion of the bearing housing is in contacting engagement with an outer surface of the bearing member to facilitate absorption of vibration energy from the bearing,

wherein the brush card mount is at least partially disposed within the peripheral lip portion of the end cap and in contacting engagement therewith, the brush card mount comprising a vibration energy absorbing material to thereby absorb vibration energy from the end cap.

15. The electric motor according to claim 14 wherein the brush card mount includes an outer portion, the outer portion disposed between the peripheral lip portion of the end cap and the rear end of the housing to minimize vibration energy transfer therebetween.

16. An electric motor for automotive applications and characterized by exhibiting minimal acoustic noise radiation, which comprises:

a housing having a closed housing end portion and an open housing end portion, and an internal chamber;

an armature disposed within the internal chamber and having an armature shaft and an armature core;

an end cap mounted to the open housing end portion, the end cap including a main portion and a peripheral lip portion extending in a general axial direction from the main portion, the main portion having a stamped pattern including at least one raised portion configured to minimize vibration energy transfer;

a brush card assembly including a brush card mount and a brush card supported by the brush card mount, the brush card mount being at least partially disposed within the peripheral lip portion of the end cap and in contacting engagement therewith, the brush card mount comprising a vibration energy absorbing material to thereby absorb vibration energy carried by the end cap;

first and second bearing assemblies for supporting the armature shaft for rotational movement, the first bearing assembly disposed adjacent the closed housing end portion and the second bearing assembly disposed adjacent the end cap, each bearing assembly including a bearing member and a bearing housing having an internal bore that accommodates at least a portion of the bearing member, the bearing housing comprising a vibration energy absorbing material, and being dimensioned such that portions of the bearing housing defining the internal bore are in contacting engagement with an outer surface of the bearing member to facilitate absorption of vibration energy from the sleeve member bearing;

a noise absorbing member disposed between each bearing assembly and the armature core of the armature, the noise absorbing member adapted to absorb noise from the respective bearing assembly to substantially acoustically isolate the respective housing end portion; and

an anti-vibration washer mounted to the armature shaft adjacent each bearing assembly, the anti-vibration washer configured to absorb energy transferred along the armature shaft.

17. The electric motor according to claim 16 wherein the brush card mount includes a first annular portion disposed within the peripheral lip portion of the end cap in contacting engagement therewith to absorb vibration energy carried by the end cap, and a second annular portion disposed between the peripheral lip portion of the end cap and the housing to minimize vibration energy transfer therebetween.

18. The electric motor according to claim 17 wherein the bearing housing of each bearing assembly includes:

a base defining a central axis and having an internal bore for accommodating the bearing member and being dimensioned such that portions of the bearing housing defining the internal bore are in contacting engagement with an outer surface of the bearing member to facilitate absorption of vibration energy from the sleeve member bearing; and

a plurality of mounting projections extending in a general axial direction from the base, the mounting projections arranged to surround at least a portion of the bearing member to facilitate retention of the bearing member within the internal bore.

19. The electric motor according to claim 18 further including energy absorbing material at least partially surrounding each bearing housing to absorb residual acoustic energy.

20. The electric motor according to claim 16 wherein the housing defines a main body section having an internal cross-sectional dimension, the main body section defining a length ranging from about 0.50 to about 0.80 times the distance of the internal dimension whereby a reactive acoustic field is created about the housing to counteract an active acoustic field generated during operation thereof.