Refrigeration – Automatic control – Of external fluid or means
Reexamination Certificate
1999-11-04
2001-01-09
Doerrler, William (Department: 3744)
Refrigeration
Automatic control
Of external fluid or means
C062S131000, C062S140000, C416S039000, C416S174000, C417S014000, C417S423900
Reexamination Certificate
active
06170275
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
This invention relates generally to fans suitable for use in a humid atmosphere, and more particularly to such a fan provided in an evaporator compartment of a refrigerator for circulating a cooling air through storage compartments.
2. Description of the prior art
A fan has conventionally been provided in an evaporator compartment of a household refrigerator for circulating a cooling air through storage compartments.
FIG. 12
illustrates one of such conventional fans. An evaporator
2
is provided in the lower interior of an evaporator compartment
1
. A fan
3
is provided over the evaporator
2
in the evaporator compartment
1
. The fan
3
comprises an electric motor
4
, an impeller
6
mounted on a rotational shaft
5
of the motor
4
, a bell-mouthed fan casing
7
surrounding the impeller
6
.
A temperature around the fan
3
ranges between −20 and −30° C. while the evaporator
2
is in operation for cooling. On the other hand, the temperature around the fan
3
ranges between +10 and +20° C. while a heater (not shown) is turned on to apply heat to the evaporator
2
so that the same is defrosted. Thus, the temperature around the fan
3
rises during the defrosting operation and accordingly, a dew condensation tends to occur around the fan
3
. In view of this, an inner rotor type motor is usually employed as the motor
4
. A main body of the motor
4
except the shaft
5
is covered with a motor cover
8
so that water is prevented from penetrating the inside of the motor
4
. However, the inner rotor type motor is disadvantageous in that an axial dimension thereof is increased.
To overcome the above-described disadvantage, the prior art has proposed employment of an outer rotor type motor as the fan motor. In this case, the impeller is provided integrally on the outer periphery of a rotor yoke of a rotor. In the outer rotor type motor, the axial dimension thereof can be rendered smaller than in the inner rotor type motor
4
. However, in the fan comprising the outer rotor type motor and the impeller provided on the outer periphery of the rotor yoke, the overall motor cannot be covered with a cover from the point of view of its structure. As a result, water tends to penetrate the inside of the motor. In particular, a gap between the rotor and the stator of the motor cannot be avoided such that water penetrates the inside of the motor through the gap. In this case, the stator, which is a principal electrical component of the motor, may be covered with a molded layer molded from a synthetic resin so that water can be prevented from penetrating the inside of the motor, but yet it is desirable to prevent water from penetrating the overall inside of the motor.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a fan which comprises an outer rotor type motor for reduction in the axial dimension thereof and yet which can prevent water from penetrating the inside of the motor.
The present invention provides a fan comprising a motor frame made of a synthetic resin and having a bracket insertion hole, a bracket including a cylindrical portion fitted into the bracket insertion hole of the motor frame so as to project from the motor frame, the bracket further including a bearing, and a stator including a stator core, a stator coil provided on the stator core, and a molded layer molded from a synthetic resin so as to cover both of the stator core and the stator coil. The stator is disposed on an outer periphery of the cylindrical portion projecting from the bracket insertion hole so as to be supported by the cylindrical portion and the motor frame. The fan further comprises a rotor including a rotational shaft inserted into the cylindrical portion so as to be rotatably mounted via the bearing on the bracket and having both ends, a rotor yoke provided on one end of the shaft opposite to the motor frame so as to cover the stator, and a rotor magnet provided on an inner circumferential face of the rotor yoke so as to be opposed to an outer circumferential face of the stator core with a gap therebetween. The fan further comprises an impeller provided on an outer circumference of the rotor yoke so as to be rotated with the rotor yoke, and a sealing cylindrical portion provided on a circumferential edge of the bracket insertion hole so as to be integral with the motor frame. The sealing cylindrical portion is fitted into a space defined between the cylindrical portion of the bracket and the molded layer.
According to the above-described construction, the outer rotor type motor is employed as the fan motor and the impeller is provided on the outer circumference of the rotor yoke. Consequently, the axial dimension of the motor can be reduced. Further, the sealing cylindrical portion is provided on the circumferential edge of the bracket insertion hole and fitted into the space defined between the cylindrical portion and the molded layer. Consequently, since an area of contact between the motor frame and the molded layer and an area of contact between the motor frame and the bracket are increased, a high sealing performance can be ensured between the motor frame and the molded layer and between the motor frame and the bracket.
When water penetrates a joint of the motor frame and the molded layer, the water would move toward the sealing cylindrical portion due to capillarity, further penetrating the inside of the stator. In view of this drawback, a circumferentially extending generally annular space is preferably defined in a joint of the motor frame and the molded layer. Consequently, even when the water penetrates the joint of the motor frame and the molded layer and moves toward the sealing cylindrical portion due to capillarity, the space interrupts the capillarity, thereby preventing the water from penetrating the inside of the motor.
The rotor yoke preferably has one of two axial ends located at the motor frame side and being open and the other axial end being closed so that the rotor yoke is generally cup-shaped. In this case, the rotor yoke is disposed to be inclined downward from said other end thereof toward said one end. Even when water penetrates the inside of the rotor yoke, the water efficiently flows outward from said one axial end of the rotor yoke. Since the rotor yoke is a rotating member, the water having penetrated the inside of the rotor yoke is efficiently discharged outward upon rotation of the rotor yoke. Consequently, the water can be prevented from remaining inside the rotor yoke.
The fan further comprises a motor support provided on the motor frame so as to be located to be subjected to an air flow set up by the impeller and an air-flow guide provided so as to be located to be subjected to the air flow set up by the impeller, the air-flow guide guiding the air flow set up by the impeller toward an outer circumference. In this case, the air-flow guide has a recess in which the motor support is placed. Turbulent flow of air can be prevented since the air-flow set up by the fan is smoothly guided toward the outer circumference by the air-flow guide. This increases an amount of air-flow set up by the fan and reduces noise. Further, as the result of the above-described construction, the air-flow guide and the motor frame are axially overlapped. Moreover, the air-flow guide has the recess in which the motor support is placed. Consequently, an increase in the axial dimension of the motor frame due to provision of the air-flow guide can be limited. The air-flow guide is preferably provided on the motor frame.
REFERENCES:
patent: Re. 32027 (1985-11-01), Hyatt et al.
patent: 3932070 (1976-01-01), Porter et al.
patent: 4724678 (1988-02-01), Pohl
patent: 4852361 (1989-08-01), Oike
Ochiai Koichiro
Ueno Shunji
Doerrler William
Kabushiki Kaisha Toshiba
Norman Marc
Pillsbury Madison & Sutro LLP
LandOfFree
Fan for refrigerator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fan for refrigerator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fan for refrigerator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2464306