WO2019164108A1

WO2019164108A1 - Brushless dc motor for laundry dryer

Info

Publication number: WO2019164108A1
Application number: PCT/KR2018/015527
Authority: WO
Inventors: Jeong Cheol Jang; Gyeong Sik Yang; Seung Ju Park
Original assignee: New Motech Co., Ltd.
Priority date: 2018-02-23
Filing date: 2018-12-07
Publication date: 2019-08-29
Also published as: KR102020653B1; KR20190101716A

Abstract

The brushless DC (BLDC) motor for a laundry dryer according to the present invention comprises a stator assembly 20 which comprises a stator core 21, upper and lower insulators 22, 23 coupled to the upper part and lower part of the stator core 21 and a coil 24 wound on a plurality of teeth projecting toward the inner side of the stator core 21; a rotor assembly 40 which comprises a main shaft 41 and a rotor core 43 coupled to the main shaft 41 and located inside the stator assembly 20 to rotate; an upper housing 10 coupled to the upper part of the stator core 21; and a lower housing 30 coupled to the lower part of the stator core 21, wherein the BLDC motor for a laundry dryer further comprises a thermal protector located in the upper part of the coil 24 wound on the teeth to be electrically connected to the coil 24.

Description

BRUSHLESS DC MOTOR FOR LAUNDRY DRYER

The present invention relates to a motor for a laundry dryer. More specifically, the present invention relates to a brushless DC (BLDC) motor for a laundry dryer, capable of easily controlling the motor by applying a brushless DC motor to the laundry dryer, managing the motor in a stable way when the motor is over-heated, and increasing driving efficiency of the motor.

In general, laundry dryers include drums for accommodating laundry, heaters for increasing the temperature in order to dry laundry inside the drums, driving belts for rotating the drums, and motors for rotating the drums by the driving belts to promote the drying of the laundry. The motors used in the laundry dryers mainly use single-phase AC motors. Such single-phase AC motors for a laundry dryer are disclosed in US Patent Nos. 7,609,491, 7,732,960, etc.

Meanwhile, BLDC motors refer to brushless DC motors, and have the advantages of easily controlling constant velocity and variable velocity of the motor, and having relatively higher power density and efficiency than the AC motors. Accordingly, if the conventional AC motors used in laundry dryers could be replaced with BLDC motors, it is expected that laundry dryers having much higher efficiency could be implemented.

Another advantage of the BLDC motors is that considering the operation of the motor is electronically controlled, if a temperature sensor is interlocked with a controller, the controller can block a current when the motor is over-heated, thereby easily handling dangerous situations.

However, in the case of devices which operate at a high temperature by heaters, such as laundry dryers, additional safety devices may be necessary rather than relying on controllers in the case of the over-heating since there is even a slightest possibility that the controllers may malfunction due to the high temperature.

Accordingly, the present inventors intend to suggest a BLDC motor for a laundry dryer, capable of blocking a current flowing in the coil without using a controller when the motor is over-heated, while applying the BLDC motor to the laundry dryer.

It is an object of the present invention to provide a BLDC motor for a laundry dryer, capable of increasing operation efficiency of the laundry dryer.

It is another object of the present invention to provide a BLDC motor for a laundry dryer, capable of stably managing the motor of the laundry dryer when the motor of the laundry dryer is over-heated, instead of relying on a controller of the BLDC motor.

The above objects of the present invention and other inherent objects could all be easily achieved by the present invention explained in the following.

The BLDC motor for a laundry dryer according to the present invention comprises a stator assembly 20 including a stator core 21, upper and

lower insulators

22, 23 coupled to the upper part and lower part of the stator core 21 and a coil 24 wound on a plurality of teeth projecting toward the inner side of the stator core 21; a rotor assembly 40 including a main shaft 41 and a rotor core 43 coupled to the main shaft 41 and located inside the stator assembly 20 to rotate; an upper housing 10 coupled to the upper part of the stator core 21; and a lower housing 30 coupled to the lower part of the stator core 21; wherein the BLDC motor for a laundry dryer further comprises a thermal protector located in the upper part of the coil 24 wound on the teeth to be electrically connected to the coil 24.

The present invention may further comprise a stator cover 28 coupled to the upper part of the upper insulator 22 so that the thermal protector is fixed to the upper part of the coil.

In the present invention, it is preferable that the stator cover 28 has a plurality of guide protrusions 28B formed to project downward and be located between distal ends of the teeth adjacent to each other.

In the present invention, it is preferable that the upper part of the stator cover 28 has a plurality of heat emitting holes 28C formed.

The BLDC motor for a laundry dyer according to another aspect of the present invention comprises a stator assembly 20 including a stator core 21, upper and

lower insulators

22, 23 coupled to the upper part and lower part of the stator core 21 and a coil 24 wound on a plurality of teeth projecting toward the inner side of the stator core 21; a rotor assembly 40 including a main shaft 41 and a rotor core 43 coupled to the main shaft 41 and located inside the stator assembly 20 to rotate; an upper housing 10 coupled to the upper part of the stator core 21; a lower housing 43 coupled to the lower part of the stator core 21; a centrifugal actuator 45 coupled to a part of the main shaft 41 projecting toward the upper housing 10; and a sliding collar 46 coupled to the upper part of the centrifugal actuator 45 and conducting a sliding movement by operation of the centrifugal actuator 45.

The BLDC motor for a laundry dryer according to the present invention has an effect of increasing operation efficiency of the laundry dryer and stably handling the over-heating.

Fig. 1 is a top perspective view illustrating a motor for a laundry dryer according to the present invention;

Fig. 2 is a bottom perspective view illustrating the motor for a laundry dryer according to the present invention;

Fig. 3 is an exploded perspective view illustrating the motor for a laundry dryer according to the present invention;

Fig. 4 is a perspective view illustrating a rotor assembly of the motor for a laundry dryer according to the present invention;

Fig. 5 is a perspective view illustrating a stator assembly of the motor for a laundry dryer according to the present invention;

Fig. 6 is an exploded perspective view illustrating the state in which a stator cover is separated from the stator assembly of the motor for a laundry dryer according to the present invention; and

Fig. 7 is a three-phase circuit diagram in which a thermal protector is applied to the motor for a laundry dryer according to the present invention.

Hereinafter, the present invention will be explained in more detail with reference to the accompanied drawings.

Fig. 1 is a top perspective view illustrating a motor for a laundry dryer according to the present invention, Fig. 2 is a bottom perspective view illustrating the motor for a laundry dryer according to the present invention, and Fig. 3 is an exploded perspective view illustrating the motor for a laundry dryer according to the present invention.

As illustrated in Fig. 1 to Fig. 3, the motor for a laundry dryer according to the present invention includes an upper housing 10, a stator assembly 20, a lower housing 30 and a rotor assembly 40.

The upper housing 10 is coupled to the upper part of a stator core 21 of the stator assembly 20. The upper housing 10 covers the upper part of the stator assembly 20, thereby playing a role in protecting an upper insulator 22 coupled to the stator core 21, a coil 24, a centrifugal actuator 45 of the rotor assembly 40, etc. An upper bearing mounting part 10A projecting upward is formed in the center part of the upper housing 10. An upper bearing 47 supporting the rotation of a main shaft 41 is inserted into the inside of the upper bearing mounting part 10A, and an upper buffering member 11 is coupled to the outside thereof. The upper buffering member 11 uses buffering materials such as rubber, and absorbs the vibration of the motor and prevents noise when the motor for a laundry dryer is coupled to a set of the laundry dryer.

The main shaft 41 penetrates into the center part of the upper housing 10, and a pulley 42 is coupled to the upper end of the main shaft 41. At one side of the upper housing 10, a roller supporting part 10B projecting upward is formed. A roller 12 is rotatably coupled to the roller supporting part 10B to rotate by a roller shaft 14. The pulley 42 and the roller 12 rotate together by a driving belt 13. The roller 12 is configured to rotate the drum (not illustrated) which accommodates the laundry.

In the housing 10, an opening part 10C penetrating into the inside is formed. A sliding collar 46 of the rotor assembly 40 is located in the opening part 10C. A switch assembly 15 is coupled to cover the opening part 10C.

The lower housing 30 is coupled to the lower part of the stator core 21 of the stator assembly 20. A lower bearing mounting part 30A projecting downward is formed in the center part of the lower housing 30. A lower bearing 48 supporting the rotation of the main shaft 41 is inserted into the inside of the lower bearing mounting part 30A, and a lower buffering member 31 is coupled to the outside thereof. The lower buffering member 31 uses buffering materials such as rubber, like the upper buffering member 11, and absorbs the vibration of the motor and prevents noise when the motor for a laundry dryer is coupled to a set of the laundry dryer.

The stator assembly 20 allows each of the teeth to have specific polarity by application of external power, to form a varying magnetic field, thereby rotating the rotor assembly 40. The detailed constitution of the rotor assembly 40 will be explained with reference to Fig. 4.

Fig. 4 is a perspective view illustrating the rotor assembly 40 of the motor for a laundry dryer according to the present invention.

When referring to Fig. 4, the rotor assembly 40 of the present invention includes the main shaft 41, the pulley 42, a rotor core 43, a rotor mold 44, the centrifugal actuator 45, the sliding collar 46, the upper bearing 47 and the lower bearing 48.

The pulley 42 is coupled to the upper end of the main shaft 41. The rotor core 43 is located approximately in the center part of the main shaft 41 to be fixed and coupled to the main shaft 41. The rotor mold 44 is formed around the rotor core 43, and a plurality of magnets (not illustrated) is inserted in the rotor core 43 in the longitudinal direction. The rotor mold 44 is preferably formed by an insert injection molding in the state where the main shaft 41, the rotor core 43 and the magnets are located in an injection mold.

The centrifugal actuator 45 is located at the upper side of the rotor core 43, and rotates together with the main shaft 41. The rotor core 43 is located in the center part of the stator assembly 20, and the rotor core 43 rotates when power is applied to the stator assembly 20. When the rotor core 43 rotates, the main shaft 41 rotates, and accordingly, the centrifugal actuator 45 and the sliding collar 46 coupled to the centrifugal actuator 45 rotate together. When the centrifugal actuator 45 reaches at a certain rotation speed, it operates to push the sliding collar 46 to slide upward. When the sliding collar 46 moves upward, it mechanically operates the switch assembly 15, thereby operating a heater (not illustrated) which is installed in the set of the laundry dryer to increase the temperature inside the drum. When the operation of the laundry dryer is stopped, the centrifugal actuator 45 operates to slidingly move the sliding collar 46 in the opposite direction, thereby mechanically shifting the heater operation switch of the switch assembly 15 to off. The detailed constitution and operating principle of the centrifugal actuator 45 are disclosed in expired US Patent No. 5,153,471, the disclosure of which is hereby incorporated by reference within the necessary scope.

The upper bearing 47 and the lower bearing 48, which are to support the rotation of the main shaft 41, are coupled to the upper part and lower part of the main shaft 41, respectively, to rotate. As mentioned above, the upper bearing 47 is coupled to the upper bearing mounting part 10A of the upper housing 10, and the lower bearing 48 is coupled to the lower bearing mounting part 30A of the lower housing 30.

Fig. 5 is a perspective view illustrating the stator assembly 20 of the motor for a laundry dryer according to the present invention, and Fig. 6 is an exploded perspective view illustrating the state in which a stator cover 28 is separated from the stator assembly 20 of the motor for a laundry dryer according to the present invention.

When referring to Fig. 5 and Fig. 6 together, the stator assembly 20 of the present invention includes the stator core 21, the upper insulator 22, the lower insulator 23, the coil 24, a power connector 25,

thermal protectors

26, 27 and the stator cover 28.

The rotor core 43 of the rotor assembly 40 is located in the center part of the stator core 21, and the stator core 21 has a plurality of teeth projecting toward the inner side so as to face the rotor core 43. The upper and

lower insulators

22, 23 made of insulating materials are coupled to the upper part and lower part of the stator core 21. Accordingly, the upper part and lower part of the teeth projecting toward the inner side of the stator core 21 are insulated by the upper and

lower insulators

22, 23, and the inner side of the teeth is also insulated by the upper and

lower insulators

22, 23 or an additional insulating film, etc. The coil 24 is wound on each of the insulated teeth. Since the motor for a laundry dryer according to the present invention uses a BLDC motor, the coil 24 according to u, v and w phases is wound on each of the teeth. The wound coil is wired by the power connector 25, and external power is supplied to the coil 24 through the power connector 25.

The

thermal protectors

26, 27 are electrically connected to the coil to block a current flowing in the coil by opening the coil when the temperature rises over a certain temperature due to causes such as overcurrent flowing in the coil, etc. The number of thermal protectors is not particularly limited, but it is preferable to apply two thermal protectors as illustrated in Fig. 6 in order to effectively block the current of three-phase wires. In the present invention, as illustrated in Fig. 6, the first thermal protector 26 and the second thermal protector are installed. The first and second

thermal protectors

26, 27 are laid right above the coil wound on the teeth. Therefore, the stator cover 28 is coupled to the upper insulator 22 in order to fix the locations of the first and second

thermal protectors

26, 27.

The stator cover 28 is coupled to the upper part of the upper insulator 22, and the first and second

thermal protectors

26, 27 are coupled to be fixed between the coil 24 and the inside surface of the stator cover 28 not to move. The manner of coupling of the stator cover 28 and the upper insulator 22 is not particularly limited. In Fig. 6, a plurality of coupling protrusions 22A is formed in the upper insulator 22, a coupling groove 28A is formed in the location corresponding to the coupling protrusion 22A on the side surface of the stator cover 28, to apply the coupling manner of inserting and coupling the coupling protrusion 22A into the coupling groove 28A. The number of coupling protrusions 22A and coupling grooves 28A is not particularly limited, but it is preferable that three or more of them are applied to ensure solid coupling.

A guide protrusion 28B is formed in the lower part of the stator cover 28 to project downward and be located between distal ends of two teeth adjacent to each other. The guide protrusion 28B prevents the coil 24 from projecting through a gap between the teeth. When the thermal protectors are installed in the wound coil 24, the wound coil may be loosened, and accordingly, when the coil projects through a space between the teeth, the operation or performance of the motor may be seriously influenced by, for example, the contact of the coil with the rotor, etc. Therefore, in order to prevent the above problem, the stator cover 28 has the guide protrusion 28B formed. The number of guide protrusions 28 is not particularly limited, but it is preferable to form the guide protrusions with the number of the thermal protectors or more. A plurality of heat emitting holes 28C is formed in the upper part of the stator cover 28 to allow the heat generated by the coil 24 to be discharged. The number of emitting holes 28C is not particularly limited, but could be properly applied according to a design environment.

Fig. 7 is a three-phase circuit diagram in which the

thermal protectors

26, 27 are applied to the motor for a laundry dryer according to the present invention. Fig. 7 illustrates an embodiment in which for the

thermal protectors

26, 27 according to the present invention, the first thermal protector 26 and the second thermal protector 27 are electrically connected on the U-phase and V-phase, respectively, of the three-phase circuit. In the case of BLDC motors, an additional temperature sensor may be installed and a control circuit may block a current supplied to the coil. However, the

thermal protectors

26, 27 of the present invention are electrically connected directly to the coil to block a current by opening the coil, and accordingly, the overheating by the control failure can be surely prevented. Furthermore, the thermal protectors may be utilized as a secondary safety device together with the conventional temperature sensor manner.

The explanation in the present invention provided above is merely to provide examples to help understand the present invention, and is not intended to limit the scope of the present invention. The explanation in the present invention shall be defined by the accompanying claims, and it should be interpreted that simple modifications or alternations of the present invention made within the scope of the claims fall within the protection scope of the present invention.

Claims

A brushless DC (BLDC) motor for a laundry dryer, comprising:

a stator assembly 20 comprising a stator core 21, upper and lower insulators 22, 23 coupled to the upper part and lower part of the stator core 21 and a coil 24 wound on a plurality of teeth projecting toward the inner side of the stator core 21;

a rotor assembly 40 comprising a main shaft 41 and a rotor core 43 coupled to the main shaft 41 and located inside the stator assembly 20 to rotate;

an upper housing 10 coupled to the upper part of the stator core 21; and

a lower housing 30 coupled to the lower part of the stator core 21,

the BLDC motor for a laundry dryer further comprising:

a thermal protector located in the upper part of the coil 24 wound on the teeth to be electrically connected to the coil 24.
The BLDC motor for a laundry dryer of claim 1, further comprising:

a stator cover 28 coupled to the upper part of the upper insulator so that the thermal protector is fixed to the upper part of the coil.
The BLDC motor for a laundry dryer of claim 2, wherein the stator cover 28 has a plurality of guide protrusions 28B formed to project downward and be located between distal ends of the teeth adjacent to each other.
The BLDC motor for a laundry dryer of claim 2, wherein the upper part of the stator cover 28 has a plurality of heat emitting holes 28C formed.
A brushless DC (BLDC) motor for a laundry dryer, comprising:

a stator assembly 20 comprising a stator core 21, upper and lower insulators 22, 23 coupled to the upper part and lower part of the stator core 21 and a coil 24 wound on a plurality of teeth projecting toward the inner side of the stator core 21;

a rotor assembly 40 comprising a main shaft 41 and a rotor core 43 coupled to the main shaft 41 and located inside the stator assembly 20 to rotate;

an upper housing 10 coupled to the upper part of the stator core 21;

a lower housing 30 coupled to the lower part of the stator core 21;

a centrifugal actuator 45 coupled to a part of the main shaft 41 projecting toward the upper housing 10; and

a sliding collar 46 coupled to the upper part of the centrifugal actuator 45 and conducting a sliding movement by operation of the centrifugal actuator 45.