Electric motor having cooling fan received in yoke

• US 20020175573A1
• Filed: 05/17/2002
• Published: 11/28/2002
• Est. Priority Date: 05/24/2001
• Status: Active Grant

• Current Assignee: ASMO Company Limited (DENSO Corporation)
• Original Assignee: ASMO Company Limited (DENSO Corporation)
• Inventors: Hayashi, Yoshiaki
• Granted Patent: US 6,703,730 B2
• Time in Patent Office: Days
• US Class Current: 310/54
• CPC Class Codes: H02K 5/10 with arrangements for protection from ingress, e.g. water or fingers
• CPC Class Codes: H02K 5/207 with openings in the casing specially adapted for ambient air
• CPC Class Codes: H02K 7/1166 comprising worm and worm-wheel structural association with bearings specially adapted for worm gear drives H02K7/081

Abstract

A yoke receives an armature and a cooling fan and has air inlet and outlet openings. A water blocking cover substantially covers the inlet and outlet openings of the yoke. The cover includes an intake duct, an exhaust duct and a partitioning member. The air is drawn from outside of the cover into the air inlet openings through the intake duct upon rotation of the fan. The air is discharged from the air outlet openings to the outside of the water blocking cover through the exhaust duct upon the rotation of the fan. The partitioning member is located in a space between the water blocking cover and the yoke and restrains free communication of the air between the intake duct and the exhaust duct through the space between the water blocking cover and the yoke.

Claims

1. An electric motor comprising:

an armature including a rotatable shaft;

a cooling fan secured to the rotatable shaft of the armature to rotate integrally with the rotatable shaft;

a yoke, which receives the armature and the cooling fan and has at least one air inlet opening and at least one air outlet opening, wherein the at least one air inlet opening is located at a first axial end portion of the yoke and penetrates through a wall of the yoke to introduce air into an interior of the yoke upon rotation of the cooling fan, and the at least one air outlet opening is located at a second axial end portion of the yoke and penetrates through the wall of the yoke to discharge the air from the interior of the yoke upon the rotation of the cooling fan; and

a water blocking cover, which substantially blocks intrusion of water into the interior of the yoke by substantially covering the at least one air inlet opening and the at least one air outlet opening of the yoke, wherein the water blocking cover includes;

an intake duct, through which the air is drawn from outside of the water blocking cover into the at least one air inlet opening upon the rotation of the cooling fan;

an exhaust duct, through which the air is discharged from the at least one air outlet opening to the outside of the water blocking cover upon the rotation of the cooling fan; and

a communication restraining portion, which is located in a space between the water blocking cover and the yoke and restrains free communication of the air between the intake duct and the exhaust duct through the space between the water blocking cover and the yoke.

2. An electric motor according to claim 1, wherein an external opening of the intake duct and an external opening of the exhaust duct are oriented generally in the direction of gravity.

3. An electric motor according to claim 1, further comprising a commutator, which is secured to the rotatable shaft near the second axial end portion of the yoke.

4. An electric motor according to claim 1, wherein the communication restraining portion is a partition wall, which is in close contact with an outer peripheral surface of the yoke and substantially partitions between the intake duct and the exhaust duct.

5. An electric motor according to claim 4, wherein the partition wall is made of a damping material.

6. An electric motor according to claim 1, wherein an external opening of the intake duct and an external opening of the exhaust duct are generally oriented in opposite directions.

7. An electric motor according to claim 1, further comprising a plurality of magnets, which are circumferentially arranged at predetermined angular intervals along an inner peripheral surface of the yoke, wherein at least one of the at least one air outlet opening is located adjacent to or in a space between the magnets.

8. An electric motor according to claim 3, further comprising

a brush holder assembly, which is stationarily secured in the electric motor near the second axial end portion of the yoke and supports a plurality of brushes that are in sliding contact with the commutator to supply electric power to the commutator, wherein the cooling fan is located on one axial side of the at least one air outlet opening, and the commutator and the brush holder assembly are located on the other axial side of the at least one air outlet opening;

and

a shielding member, which substantially separates the commutator and the brush holder assembly from the at least one air outlet opening, so that the air drawn from the at least one air inlet opening upon the rotation of the cooling fan is substantially restrained from approaching the commutator and the brush holder assembly and is discharged from the at least one air outlet opening.

9. An electric motor according to claim 8, wherein the shielding member includes:

a cylindrical portion, which has a generally cylindrical shape and includes a through hole that axially penetrates through the cylindrical portion to receive the commutator; and

a shielding portion, which has a generally annular disc shape and extends radially outwardly from an outer peripheral edge of one axial end of the cylindrical portion, which faces the commutator, wherein a connection between the cylindrical portion and the shielding portion is curved to form a curved portion and is radially opposed to the at least one air outlet opening.

10. An electric motor according to claim 9, wherein the cylindrical portion of the shielding member has a return flange, which protrudes radially outwardly from an outer peripheral edge of the other axial end of the cylindrical portion.

11. An electric motor according to claim 8, further comprising an end housing, which has an open end located adjacent to the second axial end portion of the yoke, wherein:

the second axial end portion of the yoke is an open end and is connected with the open end of the end housing; and

the shielding member is securely clamped between the yoke and the end housing through a waterproof rubber arranged along an outer peripheral edge of the shielding member.

13. An electric motor according to claim 12, wherein the air inlet openings are opposed to the cooling fan.

14. An electric motor according to claim 12, wherein:

the water blocking cover has a scroll shape, which is scrolled in a flow direction of the air about a rotational axis of the armature within the yoke; and

an external opening of the intake duct and an external opening of the exhaust duct extend in a direction tangential to the flow direction of the air within the yoke.

15. An electric motor according to claim 12, further comprising a plurality of magnets, which are circumferentially arranged at predetermined angular intervals along an inner peripheral surface of the yoke, wherein the exhaust duct is directly communicated with one of the air outlet openings, which is located between the magnets.

12. An electric motor comprising:

an armature including a rotatable shaft;

a cooling fan secured to the rotatable shaft of the armature to rotate integrally with the rotatable shaft;

a yoke, which receives the armature and the cooling fan and has a plurality of air inlet openings and a plurality of air outlet openings, wherein the air inlet openings are circumferentially arranged along an entire peripheral wall of the yoke at a first axial end portion of the yoke and penetrate through the peripheral wall of the yoke to introduce air into an interior of the yoke upon rotation of the cooling fan, and the air outlet openings are circumferentially arranged along the entire peripheral wall of the yoke at a second axial end portion of the yoke and penetrate through the peripheral wall of the yoke to discharge the air from the interior of the yoke upon the rotation of the cooling fan; and

a water blocking cover, which substantially blocks intrusion of water into the interior of the yoke by substantially covering the air inlet openings and the air outlet openings of the yoke, wherein the water blocking cover includes;

an intake duct, through which the air is drawn from outside of the water blocking cover into the air inlet openings upon the rotation of the cooling fan; and

an exhaust duct, through which the air is discharged from the air outlet openings to the outside of the water blocking cover upon the rotation of the cooling fan, wherein free communication between the intake duct and the exhaust duct is restrained between the water blocking cover and the yoke, and communication between the intake duct and the exhaust duct is allowed through the interior of the yoke.

16. An electric motor comprising:

an armature including a rotatable shaft;

a cooling fan secured to the rotatable shaft of the armature to rotate integrally with the rotatable shaft;

a yoke, which receives the armature and the cooling fan and has at least one air inlet opening and at least one air outlet opening, wherein the at least one air inlet opening is located at a first axial end portion of the yoke and penetrates through a wall of the yoke to introduce air into an interior of the yoke upon rotation of the cooling fan, and the at least one air outlet opening is located at a second axial end portion of the yoke and penetrates through the wall of the yoke to discharge the air from the interior of the yoke upon the rotation of the cooling fan;

a first water blocking cover, which substantially blocks intrusion of water into the interior of the yoke through the at least one air inlet opening by substantially covering the at least one air inlet opening and includes an intake duct, through which the air is drawn from outside of the first water blocking cover into the at least one air inlet opening upon the rotation of the cooling fan; and

a second water blocking cover, which substantially blocks intrusion of the water into the interior of the yoke through the at least one air outlet opening by substantially covering the at least one air outlet opening and includes an exhaust duct, through which the air is discharged from the at least one air outlet opening to outside of the second water blocking cover upon the rotation of the cooling fan.