Electric motor

1. An electric motor comprising:

a housing that has a bearing receiver, which is configured into a generally cylindrical shape;

a bearing that is fixed in an interior of the bearing receiver;

a rotatable shaft that is rotatably supported by the bearing and has a distal end section, which projects outward to an outside of the housing through an opening of the bearing receiver; and

a lubricant that is applied to an outer end surface of the bearing, wherein:

the rotatable shaft has a closing means for substantially closing the opening of the bearing receiver;

the closing means is at least partially received in the opening of the bearing receiver and is opposed to the outer end surface of the bearing;

the closing means is formed integrally with a speed reducing gear that is fixed to the distal end section of the rotatable shaft on a side of the closing means, which is opposite from the bearing receiver;

a distal end part of the bearing receiver, which projects toward the outside of the housing, radially inwardly protrudes;

the closing means includes a closer that axially projects from a base end surface of the speed reducing gear, which is located on a bearing receiver side of the speed reducing gear, into the opening of the bearing receiver;

the base end surface of the speed reducing gear and the closer form a stepped portion;

a gap is formed between the stepped portion and the bearing receiver to hold a leaked portion of the lubricant, which is leaked from the interior of the bearing receiver; and

an outer diameter of the speed reducing gear is larger than an outer diameter of the bearing receiver.

2. An electric motor comprising:

a housing that has a bearing receiver, which is configured into a generally cylindrical shape;

a bearing that is fixed in an interior of the bearing receiver;

a rotatable shaft that is rotatably supported by the bearing and has a distal end section, which projects outward to an outside of the housing through an opening of the bearing receiver; and

a lubricant that is applied to an outer end surface of the bearing, wherein:

the rotatable shaft has a closing means for substantially closing the opening of the bearing receiver;

the closing means is at least partially received in the opening of the bearing receiver and is opposed to the outer end surface of the bearing;

the closing means is formed integrally with a speed reducing gear that is fixed to the distal end section of the rotatable shaft on a side of the closing means, which is opposite from the bearing receiver;

a distal end part of the bearing receiver, which projects toward the outside of the housing, radially inwardly protrudes;

a flange is provided at an end of the speed reducing gear, which is located on a bearing receiver side of the speed reducing gear, to radially outwardly projects from the speed reducing gear;

the closing means includes a closer that axially projects from a base end surface of the flange, which is located on a bearing receiver side of the flange, into the opening of the bearing receiver;

the base end surface of the flange and the closer form a stepped portion;

a gap is formed between the stepped portion and the bearing receiver to hold a leaked portion of the lubricant, which is leaked from the interior of the bearing receiver; and

an outer diameter of the speed reducing gear is larger than an outer diameter of the bearing receiver.

3. The electric motor according to claim 1 , wherein the speed reducing gear is a worm.

4. The electric motor according to claim 1 , wherein the bearing is a plain bearing.

5. An electric motor comprising:

a housing that has a bearing receiver, which is configured into a generally cylindrical shape;

a bearing that is fixed in an interior of the bearing receiver;

a rotatable shaft that is rotatably supported by the bearing and has a distal end section, which projects outward to an outside of the housing through an opening of the bearing receiver;

a closer that is configured into a generally cylindrical shape and is provided to the rotatable shaft to rotate integrally with the rotatable shaft relative to the housing, wherein the closer is at least partially received in the opening of the bearing receiver to substantially close the opening of the bearing receiver and has an outer diameter larger than an outer diameter of an adjacent part of the rotatable shaft, which is adjacent to the closer, and the closer has an opposed end surface, which is axially opposed to an outer end surface of the bearing and defines a lubricant holding space in cooperation with the outer end surface of the bearing, an inner peripheral surface of the bearing receiver and an outer peripheral surface of the rotatable shaft; and

a lubricant that is applied to the outer end surface of the bearing around the rotatable shaft in the lubricant holding space, wherein

a speed reducing gear is provided to the distal end section of the rotatable shaft on a side of the closer, which is opposite from the bearing receiver;

a base end surface of the speed reducing gear, which is located on a bearing receiver side of the speed reducing gear, and the closer form a stepped portion; and

a gap is formed between the stepped portion and the bearing receiver to hold a leaked portion of the lubricant, which is leaked from the interior of the bearing receiver;

a distal end part of the bearing receiver, which projects toward the outside of the housing, radially inwardly protrudes; and

an outer diameter of the speed reducing gear is larger than an outer diameter of the bearing receiver.

6. The electric motor according to claim 5 , wherein the speed reducing gear is a worm.

7. The electric motor according to claim 5 , wherein a flange, which projects radially outward from the speed reducing gear, is axially interposed between the speed reducing gear and the closer.

8. The electric motor according to claim 7 , wherein: a base end surface of the flange, which is located on a bearing receiver side of the flange, and the closer form a stepped portion; and a gap is formed between the stepped portion and the bearing receiver to hold a leaked portion of the lubricant, which is leaked from the interior of the bearing receiver.

9. The electric motor according to claim 5 , wherein the bearing is a plain bearing.