Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-06-06
2003-03-04
Le, Dang Dinh (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S089000, C310S052000, C310S058000, C310S059000
Reexamination Certificate
active
06528919
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-175152 filed on Jun. 12, 2000.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a brushless motor used as a blower motor of a vehicle air conditioning system.
2. Description of Related Art
One type of previously proposed brushless motor used as a blower motor of a vehicle air conditioning system includes a stator, a rotor and a circuit board. The stator is secured to one side of a motor.holder. The circuit board is secured to the other side of the motor holder and includes an excitation circuit for supplying exciting current to the stator. The circuit boar is covered with a case connected to the motor holder. When the exciting current is supplied to the stator, the rotor is rotated to rotate a fan to blow air.
During the operation of the brushless motor, excessively high internal temperature of the motor causes the exciting current to be reduced, leading to a reduction in an output power of the motor and also causes failure of electronic components. Thus, in the previously proposed brushless motor, a heat source (e.g., the stator or the elements on the circuit board) located inside of the motor is cooled with cooling air during the operation of the motor. However, in this case, during rain, car washing or the like, water droplets can be drawn into the interior of the motor along with the cooling air. Some such motors have a structure that restrains the water droplets from being drawn into the interior of the motor.
Specifically, with reference to
FIG. 6
, in one previously proposed brushless motor, a ventilation chamber
53
is defined between a motor holder
51
and a base case
52
connected thereto. Cooling air is drawn into an interior (stator side) of the motor through the ventilation chamber
53
and a guide hole
54
. With this cooling air, the heat source located in the interior of the motor is cooled. Furthermore, as shown in
FIGS. 6 and 7
, a water reservoir
55
for accumulating the water droplets is formed in the ventilation chamber
53
. In the water reservoir
55
, a side wall
56
protrudes from a base of the base case
52
. The water droplets drawn along the cooling air are accumulated within the water reservoir
55
, so that the water droplets are not further drawn toward the interior of the motor.
In this motor, the motor holder
51
is not in sealed contact with the base case
52
. Rather, the motor holder
51
simply abuts against the base case
52
, allowing the water to flow through the contact surface between the motor holder
51
and the base case
52
. Thus, the water can penetrate into the interior (stator side) of the motor through the contact surface between the motor holder
51
and the base case
52
. However, as disclosed in Japanese Patent Application No. 11-121489, in the previously proposed brushless motor that is shown in
FIGS. 6
to
8
, water-flow interrupting holes (water draining portions.)
57
a
and
57
b
are provided in the connection or contact surface between the motor holder
51
and the base case
52
to restrain the penetration of the water into the interior of the motor. With reference to
FIG. 8
, notches
58
a
and
58
b
are formed in the base case
52
. A water-flow interrupting hole
57
a
is formed by the notch
58
a
and a lower side of the motor holder
51
, and a water-flow interrupting hole
57
b
is formed by the notch
58
b
and the side of the motor holder
51
. In the water-flow interrupting hole
57
a
, a projection
59
projects from the side of the motor holder
51
to contacts, the notch
58
a
of the base case
52
. With this arrangement, the water droplets penetrating the connection between the motor holder
51
and the base case
52
are directed downward, as indicated with an arrow in FIG.
8
. The projection
59
is not entirely, continuously engaged with the notch
58
a
. In other words, a base end of the projection
59
is spaced from a base of the notch
58
a
. As a result, the water guided downward in the water-flow interrupting hole
57
a
is not guided upward in the water-flow interrupting hole
57
a
to further penetrate through the connection between the motor holder
51
and the base case
52
. Similarly, in the water-flow interrupting hole
57
b
, the water is guided downward and does not further penetrate through the connection between the motor holder
51
and the base case
52
. Thus, the water-flow interrupting holes
57
a
and
57
b
in the connection between the motor holder
51
and the base case
52
cause the water droplets to drop therein by gravity.
In the ventilation chamber
53
, the cooling air flows toward the stator side. However, in the case of the brushless motor having the water-flow interrupting holes
57
a
and
57
b
, a portion of the cooling air leaks from the ventilation chamber
53
through the water-flow interrupting holes
57
a
and
57
b
. If the brushless motor is located near legs of a vehicle occupant in a vehicle cabin, the leaked cooling air may cause an unpleasant sensation to the vehicle occupant.
SUMMARY OF THE INVENTION
The present invention addresses the above disadvantages. Thus, it is an objective of the present invention to provide a brushless motor that includes a water draining portion for draining water out of the motor and effectively reduces or restrains leakage of cooling air through the water draining portion.
To achieve the objective of the present invention, there is provided a brushless motor including a motor holder and a case connected thereto. The motor holder includes a stator secured thereto. The stator rotatably supports a rotor. The motor holder also has a circuit board connected thereto. The circuit board has an excitation circuit for supplying exciting current to the stator. The case covers the circuit board and defines a ventilation chamber in cooperation with the motor holder. The ventilation chamber, includes an air inlet portion, an air outlet portion and a water draining portion. The air inlet portion is in communication with an atmosphere. The air outlet portion is in communication with the stator. The water draining portion drains water introduced into the ventilation chamber out of the brushless motor. The brushless motor provides a flow of cooling air passing through the ventilation chamber via the air inlet portion and the air outlet portion toward the stator for cooling heat generated during rotation of the rotor. At least one of the motor holder and the case has one or more guide ribs arranged in the ventilation chamber to define an air passage for guiding the cooling air from the air inlet portion to the air outlet portion. The water draining portion is located outside of the air passage.
REFERENCES:
patent: 3751699 (1973-08-01), Gleichman
patent: 5077503 (1991-12-01), Tamura et al.
patent: 6107708 (2000-08-01), Yamaguchi et al.
patent: A-6-84771 (1994-12-01), None
patent: A-11-332203 (1999-11-01), None
patent: A-2000-316247 (2000-11-01), None
Fujii Yoshikazu
Miyazawa Kazuhiro
Tsuchida Masumi
Asmo Co. Ltd.
Dinh Le Dang
Law Offices of David G. Posz
LandOfFree
Brushless motor having water draining portion does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Brushless motor having water draining portion, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Brushless motor having water draining portion will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3001939