WO2012081929A2

WO2012081929A2 - Air purifier and fan control method thereof

Info

Publication number: WO2012081929A2
Application number: PCT/KR2011/009712
Authority: WO
Inventors: Wang-Jun Lee; Joong-Bae Shin; Gue-Ryang Lee
Original assignee: Woongjin Coway Co Ltd
Current assignee: Coway Co Ltd
Priority date: 2010-12-16
Filing date: 2011-12-16
Publication date: 2012-06-21
Anticipated expiration: 2013-06-16
Also published as: WO2012081929A3; KR101906347B1; JP5725385B2; JP2014502560A; KR20120067965A

Abstract

A fan control method of an air purifier includes: an operating mode determining process of determining an operating strength of the air purifier; a first fan motor driving process of operating a first fan motor at a first operating speed corresponding to the operating strength, such that a fan coupled to the first fan motor is rotated; and a second fan motor driving process of operating a second fan motor at a second operating speed altered from the first operating speed by a preset value, such that a fan coupled to the second fan motor is rotated.

Description

AIR PURIFIER AND FAN CONTROL METHOD THEREOF

The present invention relates to an air purifier including a plurality of fans, and a control method for fan motors thereof.

The atmospheric layer of the earth on which we live has been polluted by various pollutants emitted from industrial sites and homes. Many efforts to solve the serious problems of atmospheric pollution have been attempted worldwide.

An air purifier is a device designed to purify indoor air by removing a variety of dust particles and bacteria therefrom or by deodorizing indoor air by removing the smell of cigarettes, the smell of sweat, and so on.

Such an air purifier includes a fan unit for drawing in indoor air and forcibly expelling the indrawn air; and a filter member for filtering dust particles or bacteria or deodorizing indoor air by removing odors in the air circulated indoors by the operation of the fan unit.

The fan unit is provided with a motor and a fan. When the motor is rotated, the fan draws indoor air into, and discharges indoor air from, the air purifier. The filter member is provided with a plurality of filters. When the air passes through the air purifier by the operation of the fan unit, the filters deodorize smells and filter dust particles or bacteria contained in the air through dust collection or the like.

The fan may be an impeller fan or a sirocco fan.

Recent air purifiers are provided with a filter member that generates anions. Such an air purifier supplements naturally-present anions reduced by the pollution of indoor air, which may provide a pleasant indoor environment.

However, in such a conventional air purifier, a fan unit is configured such a manner that a single motor may be coupled to a single fan, or a single motor may be coupled to two fans. Therefore, the air cleaning efficiency of the air purifier may be lowered. In addition, if the fan of the fan unit is provided with an impeller fan, noise and vibrations may be seriously generated during the operation of the air purifier.

An aspect of the present invention provides an air purifier including a plurality of fans and a fan control method thereof.

According to an aspect of the present invention, there is provided a fan control method of an air purifier, including: an operating mode determining process of determining an operating strength of the air purifier; a first fan motor driving process of operating a first fan motor at a first operating speed corresponding to the operating strength, such that a fan coupled to the first fan motor is rotated; and a second fan motor driving process of operating a second fan motor at a second operating speed altered from the first operating speed by a preset value, such that a fan coupled to the second fan motor is rotated.

The preset value may be determined in consideration of at least one of a load amount of the fan motors, a size of the fans, and a configuration of the air purifier.

In the second fan motor driving process, the second fan motor may be operated after a preset period of time has elapsed from the initiation of the operation of the first fan motor.

When the second operating speed is higher than the first operating speed, the second fan motor driving process may be performed first, and the first fan motor driving process may be then performed after a preset period of time has elapsed.

The preset period of time may be determined in consideration of at least one of an inductance characteristic, a driving voltage, and a load amount of the fan motors.

According to another aspect of the present invention, there is provided a fan control method of an air purifier, including: an operating mode determining process of determining an operating strength of the air purifier; an operating speed setting process of setting a first operating speed and a second operating speed as operating speeds of a plurality of fan motors provided in the air purifier, wherein the first operating speed corresponds to the operating strength, and the second operating speed is determined by changing the first operating speed by a preset value; and a driving process of operating the fan motors at the set operating speed and rotating the fans coupled to the fan motors.

The driving process may include: a first fan motor operating process of operating a first fan motor rotating at the first operating speed; and a second fan motor operating process of operating a second fan motor rotating at the second operating speed after a preset period of time has elapsed.

When the second operating speed is higher than the first operating speed, the driving process may include: a second fan motor operating process of operating a second fan motor rotating at the second operating speed; and a first fan motor operating process of operating a first fan motor rotating at the first operating speed after a preset period of time has elapsed.

According to another aspect of the present invention, there is provided a fan control method of an air purifier, including: a stopping determining process of determining fan motors to be stopped among a plurality of fan motors; and a first fan motor stopping process of stopping any one of the fan motors to be stopped; and when the number of the fan motors to be stopped is two or more, a second fan motor stopping process of stopping another one of the fan motors to be stopped, after a preset period of time has elapsed from the initiation of the stopping of the first motor.

The second fan motor stopping process may be performed repetitively until the fan motors to be stopped are all stopped.

According to another aspect of the present invention, there is provided an air purifier, including: a plurality of fan motors configured to operate at operating speeds set according to a control signal; a plurality of fans coupled to the fan motors to rotate to form air flow; and a controller configured to set the operating speeds for the plurality of fan motors and transmit the control signal corresponding to the operating speeds to the fan motors.

The controller may receive an operating strength of the air purifier and set a first operating speed and a second operating speed as the operating speeds of the plurality of fan motors, wherein the first operating speed corresponds to the received operating strength, and the second operating speed is determined by changing the first operating speed by a preset value.

The controller may first operate the fan motors set to the first operating speed, and then operate the fan motors set to the second operating speeds after a preset period of time has elapsed.

According to exemplary embodiments of the present invention, an air purifier uses a plurality of fan motors. Therefore, the performance of the air purifier may be improved, and noise caused by resonance between the plurality of fan motors may be removed.

In addition, it is possible to prevent circuit malfunctions and damage to various parts, which may be caused by inductance characteristics of a plurality of fan motors during on or off switching operations thereof.

The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGS. 1A and 1B are views illustrating examples of an air purifier, to which a fan control method according to an exemplary embodiment of the present invention is applied;

FIG. 2 is a side view illustrating a case in which an air purifier including a plurality of fan motors is mounted on a wall;

FIGS. 3A and 3B are graphs showing an analysis result of noise spectrums of an air purifier using a single fan motor and an air purifier using a plurality of fan motors;

FIGS. 4A and 4B illustrate noise spectrums in a case in which an air purifier using a single fan motor and an air purifier using two fan motors are operated in a maximum operating mode at the same operating speed and at different operating speeds;

FIGS. 5A and 5B are flowcharts illustrating a control flow of a fan control method of an air purifier, according to an exemplary embodiment of the present invention;

FIG. 6 is a flowchart illustrating a control flow of a fan control method of an air purifier, according to another exemplary embodiment of the present invention; and

FIG. 7 is a flowchart illustrating a control flow when a fan motor of an air purifier is stopped, according to an exemplary embodiment of the present invention.

Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In describing the present invention, if a detailed explanation of a related known function or construction is considered to unnecessarily divert from the gist of the present invention, such explanation will be omitted but would be understood by those skilled in the art. The same or equivalent elements are referred to as the same reference numerals throughout the specification.

It will be understood that when an element is referred to as being connected with another element, it can be directly connected with the other element or may be indirectly connected with the other element with element(s) interposed therebetween. Unless explicitly described to the contrary, the word comprise and variations such as comprises or comprising, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

FIGS. 1A and 1B are views illustrating examples of an air purifier to which a fan control method according to an exemplary embodiment of the present invention is applied.

Referring to FIG. 1A, an air purifier, to which a fan control method according to an exemplary embodiment of the present invention is applied, may discharge air to both sides thereof and may be mounted on a wall.

Referring to FIG. 1B, an air purifier, to which a fan control method according to an exemplary embodiment of the present invention is applied, may be provided with a plurality of fans and a plurality of fan motors.

However, in a case in which an air purifier is provided with a plurality fan and a plurality of fan motors, noise may be generated when the plurality of fan motors are operated at the same or a similar speed, as opposed to a case in which a single motor is used. Such a noise may have a frequency band that may inconvenience users.

FIG. 2 is a side view illustrating a case in which an air purifier including a plurality of fan motors is mounted on a wall.

Referring to FIG. 2, when an air purifier 10 including a plurality of fan motors is mounted on a wall, a resonance area (a hatched area) 12 may be formed between the air purifier 10 and the wall.

The resonance area 12 is formed when the air purifier 10 is spaced apart from the wall by a support 11. The resonance area 12 is inevitably formed because the air purifier 10 cannot be entirely attached to the wall. The air purifier 10 may be spaced apart from the wall in order that air discharged from an air outlet port 12 is not disturbed by the wall.

If the resonance area 12 is formed between the air purifier 10 and the wall for the above-described reason, noise generated by the fan motors may be resonated within the resonance area 12. If the noise generated by the fan motors is resonated within the resonance area 12, a magnitude of the noise is larger than that of noise generated by an operation of a typical fan motor, which may cause inconvenience to an air purifier user.

In particular, when the operating speed of the fan motor is low, a magnitude of noise may be negligibly small. However, when the operating speed of the fan motor is high, the degree of resonance in the resonance area 12 may be rapidly increased. Hence, noise-related problems may be incurred.

In addition, referring to FIG. 1B, a plurality of fans having the same performance may be used for the stability of products. In this case, if the fan motors are operated at the same speed, it may be highly likely that noise generated by the fan motors will cause resonance in an inner space of an air purifier housing.

FIGS. 3A and 3B are graphs showing an analysis result of noise spectrums of an air purifier using a single fan motor and an air purifier using a plurality of fan motors.

Specifically, FIG. 3A is a graph showing a comparison of noise spectrums when the air purifier is operated in a minimum operating mode, that is, a silent mode. In FIG. 3A, S1 represents a noise spectrum of the air purifier using a single fan motor, and S2 represents a noise spectrum of the air purifier using a plurality of fan motors.

Referring to FIG. 3A, S1 has a higher decibel than S2 in general. In a case in which a plurality of fan motors are used, a load amount applied to one fan motor is reduced. Accordingly, the air purifier may be operated silently.

However, it can be seen from the noise spectrum S2 that a louder noise is generated in a 3-kHz frequency band, as compared to other frequency bands. In other words, when the plurality of fan motors are used, much more noise may be generated in a 3-kHz frequency band (an audio frequency band). However, when the air purifier is operated in a silent mode, the intensity of noise may be negligibly low.

FIG. 3B is a graph showing a comparison of noise spectrums when the air purifier is operated in a maximum operating mode. In FIG. 3B, S3 represents a noise spectrum of the air purifier using a single fan motor, and S4 represents a noise spectrum of the air purifier using a plurality of fan motors.

Referring to FIG. 3B, in the case of using a plurality of fan motors, a louder noise is generated in a 3-kHz frequency band, as compared to other frequency bands. In addition, the intensity of noise is significantly high in the 3-kHz frequency band, as compared to other frequency bands. In such a noise spectrum, noise in an audio frequency band is generated remarkably strongly, which may bother users. If uniform noise is generated across the entire frequency band, noise may not be recognized as serious, as in the case of white noise. Therefore, as illustrated in FIG. 3B, if a loud noise is generated in a specific frequency band, it may cause considerable emotional inconvenience to users.

Such a noise is generated when the plurality of fan motors are operated at the same or a similar speed, and thus, noise generated by the fan motors resonates. Therefore, if the cause of noise is removed, noise problems may be solved.

A control method for changing operating speeds of a plurality of fan motors in an air purifier is proposed. Differences between the operating speeds of the fan motors may be determined in a range that does not affect an air cleaning function of the air purifier.

Table 1 below shows exemplary operating speeds of fan motors in operating modes of the air purifier when the plurality of fan motors are controlled at the same speed.

Table 1

Operating mode	Operating speed of first fan motor (RPM)	Operating speed of second fan motor (RPM)
Silent mode	370	370
First gear mode	475	475
Second gear mode	580	580
Third gear mode	950	950
Automatic third gear mode	790	790

Table 2

Operating mode	Operating speed of first fan motor (RPM)	Operating speed of second fan motor (RPM)
Silent mode	370	420
First gear mode	475	525
Second gear mode	580	630
Third gear mode	950	1000
Automatic third gear mode	790	840

Referring to Table 1 above, the operating speeds of the fan motors correspond to the operating modes. In the maximum operating mode, considerable noise may be generated because the fan motors are operated at a very high speed, as compared to the silent mode.

FIG. 4A illustrates noise spectrums in a case in which an air purifier using a single fan motor and an air purifier using two fan motors are operated at an operating speed corresponding to the third gear mode of Table 1 above. In FIG. 4A, S5 represents a noise spectrum of the air purifier using a single fan motor, and S6 represents a noise spectrum of the air purifier using two fan motors.

Referring to FIG. 4A, in the case of using two fan motors in a 3-kHz frequency band (audio frequency band), a louder noise was generated as compared to the case of using a single fan motor.

Referring to Table 2 above, differences in the operating speeds of the first fan motor and the second fan motor are 50 RPM in each operating mode. However, the differences in the operating speeds of the first fan motor and the second fan motor are not necessarily 50 RPM and may be determined in consideration of at least one of a load amount of a fan motor, a size of a fan, or a configuration of an air purifier. In addition, when a difference in the operating speeds of the first fan motor and the second fan motor is excessively great, noise may be generated because the air purifier is vibrated by an unbalanced operation of the fan motor. Therefore, there is a need to pay attention to this situation.

FIG. 4B illustrates noise spectrums in a case in which an air purifier using a single fan motor and an air purifier using two fan motors are operated at an operating speed corresponding to the third gear mode of Table 2 above. In FIG. 4B, S7 represents a noise spectrum of the air purifier using a single fan motor, and S8 represents a noise spectrum of the air purifier using two fan motors.

Referring to FIG. 4B, in the case of two fan motors being used in a 3-kHz frequency band (audio frequency band), noise was almost removed. That is, a noise resonance phenomenon was disappeared.

However, in a differential control of the fan motors, it is important not to exceed the maximum operating speed of the fan motors.

FIGS. 5A and 5B are flowcharts illustrating fan control methods of an air purifier according to exemplary embodiments of the present invention.

Referring to FIG. 5A, a fan control method of an air purifier according to an exemplary embodiment of the present invention may include an operating mode determining process S10, a first fan motor driving process S20, and a second fan motor driving process S30.

The fan control method according to the exemplary embodiment of the present invention may be applied to an air purifier including a plurality of fans and a plurality of fan motors, which are coupled to the fans and drive the same.

In the operating mode determining process S10, an operating strength of the air purifier may be determined. The operating strength may be set automatically or may be information input by a user.

In the first fan motor driving process S20, a fan motor coupled to one of the fans may be operated at an operating speed corresponding to the operating strength. One of the plurality of fan motors, that is, the first fan motor, may be selected and operated at a first operating speed corresponding to the operating strength. When the first fan motor is operated, the fan coupled to the first fan motor may also be rotated.

In the second fan motor driving process S30, a fan motor coupled to one of the other fans except for the fan driven in the first fan motor driving process S20 may be operated at an operating speed altered from the operating speed by a preset value corresponding to the operating strength. That is, by operating the second fan motor at a second operating speed altered from the first operating speed by the preset value, the fan coupled to the second fan motor may be rotated. The preset value may be determined in consideration of at least one of a load amount of the fan motor, a size of the fan, or a configuration of the air purifier.

The second fan motor may indicate the entirety of fan motors, except for the first fan motor, and the second fan motor may have the second operating speed altered from the first operating speed by the preset value.

For example, when it is assumed that the air purifier is provided with three fan motors a, b and c, the fan motor a may be the first fan motor and may be operated at the first operating speed of 100 rpm. The fan motors b and c may be the second fan motors. The fan motor b may be operated at the second operating speed of 150 rpm that is altered from the first operating speed by the preset value of 50 rpm, and the fan motor c may be operated at the second operating speed of 200 rpm altered from the first operating speed by a preset value of 100 rpm.

In the first fan motor driving process S20 and the second fan motor driving process S30, the fan motors are operated at different operating speeds. Therefore, noise caused by the operation of the fan motors may be reduced.

In the second fan motor driving process S30, the second fan motor may be operated after a preset period of time has elapsed from the initiation of the operation of the first fan motor. That is, as illustrated in FIG. 5B, after the first fan motor driving process S20, it is determined whether the preset period of time has elapsed (S31). When it is determined that the preset period of time has elapsed, the second fan motor driving process S30 may be performed.

In a case in which a plurality of fan motors are used, the plurality of fan motors are switched on or off at the same timing, circuit malfunctions and part damages may be caused by inductance characteristics of the fan motors. In order to prevent this problem, the above-described process S31 is performed.

Specifically, in a case in which a plurality of fan motors are used, a counter electromotive force generated in inductors within the fan motors may be increased, as compared to a case in which a single fan motor is used. In particular, a counter electromotive force generated during on or off switching operations of the fan motors is a very high voltage, as compared to a rated voltage for operating the air purifier. Therefore, if the plurality of fan motors are switched on or off at the same time, it is highly likely that the circuit malfunctions and part damages will occur.

For example, the fan motor performs a hall sensor feedback control for 12 pulses per revolution. To this end, an input voltage of the fan motor may be regulated to be within a range of 0 V to 6.5 V. However, if a motor power is switched on or off at the same time with power supply in an initial operation or if the operating speed of the fan motor is changed, a counter electromotive force, in which inductor components of the fan motors are large, may be generated. In particular, defects of products caused by the above-described reasons may be difficult to repair or analyze. Therefore, it may be difficult to know the cause of defects.

Therefore, in a case in which the plurality of fan motors are operated, the above-described problems may be solved by sequentially operating another fan motor after a preset period of time has elapsed from the initiation of an operation of one fan motor.

The preset period of time may be determined in consideration of at least one of an inductance characteristic, a driving voltage, and a load amount of the fan motor. That is, the preset period of time may mean a time at which an inductance generated by one fan motor does not affect the operations of other fan motors.

In addition, a time necessary for a normal operation of the fan motor may be reduced by first operating fan motors whose set operating speeds are higher. The influence of the inductor appears strongly in the initial operation of the fan motor. Therefore, the influence of the inductor may be reduced if the operating speed of the fan motor is slowly increased after the operation of the fan motor. In this case, the air purifier may be operated, while minimizing interference between the plurality of fan motors.

Therefore, by comparing the first operating speed with the second operating speed, a fan motor having a higher operating speed may be operated initially, and the other fan motor may be then operated after the preset period of time has elapsed.

Referring to FIG. 6, the fan control method of the air purifier, according to the exemplary embodiment of the present invention, may include an operating mode determining process S40, an operating speed setting process S50, and a driving process S60.

In the operating mode determining process S40, an operating strength of the air purifier may be determined. The operating strength may be set automatically or may be information input by a user.

In the operating speed setting process S50, a first operating speed corresponding to the operating strength, and a second operating speed, altered from the first operating speed by a preset value, may be calculated. The calculated first and second operating speeds may be set as the operating speeds of the fan motors, respectively.

The first operating speed may be an operating speed set based on the operating strength, and the second operating speed may be an operating speed altered from the first operating speed by a preset value. The different second operating speed may be set to the respective fan motors. The second operating speed may be different from the first operating speed by the preset value. The preset value may be determined in consideration of at least one of a load amount of the fan motor, a size of the fan, or a configuration of the air purifier.

For example, when it is assumed that the air purifier is provided with three fan motors a, b and c, the first operating speed may be set to the fan motor a. The second operating speed determined by adding a preset value of 50 rpm to the first operating speed may be set to the fan motor b. The second operating speed determined by adding a preset value of 100 rpm to the first operating speed may be set to the fan motor c. In a case in which the air purifier is provided with more than three fan motors, the second operating speed may be set in the respective fan motors using the same method as described above.

In the driving process S60, some of the fan motors may be driven at the first operating speed, and others may be driven at the second operating speed. That is, by operating the fan motors according to the set operating speeds, the fans coupled to the fan motors may be rotated. In other words, noise may be reduced by operating the fan motors at different operating speeds.

In the driving process S60, the fan motors may be sequentially operated in order to prevent circuit malfunctions and part damages, which may be caused when the plurality of fan motors are switched on or off at the same time.

Specifically, in the driving process S60, a first fan motor operating process may be performed to operate the first fan motor rotating at the first operating speed. After a preset period of time has elapsed from the initiation of the operation of the first fan motor, a second fan motor operating process may be performed to operate the second fan motor rotating at the second operating speed.

That is, the first fan motor is operated and the second fan motor starts to operate after a preset time interval. The preset time interval may be determined in consideration of at least one of an inductance characteristic, a driving voltage, and a load amount of the fan motor. If the predetermined time interval elapses, an inductance generated by one fan motor may not affect the operations of other fan motors.

In addition, as described above, a time necessary for a normal operation of the fan motor may be reduced by first operating fan motors whose set operating speeds are higher. After comparing the first operating speed with the second operating speed, the fan motor operating at a high operating speed may be operated initially, and the other fan motors may be operated after the preset period of time has elapsed.

As described above, a counter electromotive force generated in the on or off switching operations of the fan motors may also be generated when the fan motors of the air purifier are initially driven or when the fan motors stop operating.

FIG. 7 is a flowchart illustrating a control flow when a fan operation is stopped, as an example of a fan control method of an air purifier according to an exemplary embodiment of the present invention.

Referring to FIG. 7, a fan control method of an air purifier according to an exemplary embodiment of the present invention may include a stopping determining process S70, a first fan motor stopping process S80, and second fan motor stopping processes S90 and S91.

In the stopping determining process S71, fan motors to be stopped among a plurality of fan motors may be determined. All or some of the fan motors may be stopped.

In the first fan motor stopping process S80, one of the fan motors to be stopped may be stopped.

In the second fan motor stopping processes S90 and S91, in a case in which the number of the fan motors to be stopped is two or more, the other fan motor may be stopped (S90) when a preset period of time has elapsed from the initiation of the first fan motor stopping process (S91). In particular, the second fan motor stopping processes S90 and S91 are performed repetitively until all the fan motors to be stopped are stopped. Therefore, the air purifier may be operated with an operating strength desired by a user or an operating strength set automatically.

That is, in a case in which the plurality of fan motors need to be stopped, the fan motors may be sequentially stopped to minimize interference between the fan motors, which occurs due to the stopping of the fan motors.

In addition, the preset period of time may be determined in consideration of at least one of an inductance characteristic, a driving voltage, and a load amount of the fan motor. That is, the preset period of time may mean a time at which an inductance generated by one fan motor does not affect the operations of other fan motors.

In addition, a time necessary for stopping all the fan motors to be stopped may be reduced by first stopping the fan motors having higher operating speeds. The influence of the inductor appears strongly in the initial stopping operation. Therefore, the influence of the inductor may be reduced after the stopping operation is started.

Although not illustrated, the air purifier according to the exemplary embodiment of the present invention may include a fan motor, a fan, and a controller.

The fan motor operates at an operating speed set according to a control signal. The fan motor may be provided in numbers. The fan is coupled to the fan motor and rotates to form air flow. The fan may be provided in numbers. Due to the air flow formed by the fan and the fan motor, outside air may be introduced into the air purifier, and air filtered within the air purifier may be discharged to the outside of the air purifier.

The air purifier is a wall mount type air purifier. Noise generated when the plurality of fan motors and the plurality of fans are rotating may be resonated in a space between the air purifier and the wall, which may cause a louder noise.

The controller may control the operating speeds of the plurality of fan motors under conditions that do not cause the resonance, so as to prevent an increase of noise caused by the resonance.

Specifically, the controller may receive the operating strength of the air purifier, which is input by the user, or the preset operating strength of the air purifier. The controller may set the first operating speed corresponding to the operating strength. In addition, based on the first operating speed, the controller may set the second operating speed to be altered from the first operating speed by a preset value, that is, the operating speed at which no resonance occurs with the fan motor operating at the first operating speed.

Then, the controller may transmit the control signal to the plurality of fan motors and operate the fan motors at the set first and second operating speeds.

In addition, the controller may sequentially start or stop operating the plurality of fan motors. Therefore, it may be possible to prevent circuit malfunctions and part damages during the on or off switching operations of the fan motors.

Specifically, if the plurality of fan motors are used, a counter electromotive force generated in inductors within the fan motors may be increased, as compared to a case in which a single fan motor is used. In particular, a counter electromotive force generated during the on or off switching operations of the fan motors is a very high voltage, as compared to a rated voltage for operating the air purifier. Therefore, if the plurality of fan motors are switched on or off at the same time, it is highly likely that the circuit malfunctions and part damages will occur.

In order to minimize the generation of the counter electromotive force, the controller may sequentially switched on or off the individual fan motors, instead of switching on or off the fan motors at the same time. That is, any one of the plurality of fan motors may be first operated, and another may be operated after a preset time interval has elapsed.

The counter electromotive force may be generated when the fan motors are stopped, as well as when the fan motors are operated. Therefore, the plurality of fan motors need to be sequentially stopped. That is, any one of the plurality of fan motors may be first stopped, and another may be stopped after a preset time interval has elapsed.

The preset time interval may be determined in consideration of at least one of an inductance characteristic, a driving voltage, and a load amount of the fan motor. If the preset time interval has elapsed, the inductance generated by one fan motor may not affect the operation and stop of other fan motors.

Moreover, if the fan motors, whose set operating speeds are higher, are operated initially, a time necessary for the normal operations of the fan motors may be reduced.

While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

A fan control method of an air purifier, comprising:

an operating mode determining process of determining an operating strength of the air purifier;

a first fan motor driving process of operating a first fan motor at a first operating speed corresponding to the operating strength, such that a fan coupled to the first fan motor is rotated; and

a second fan motor driving process of operating a second fan motor at a second operating speed altered from the first operating speed by a preset value, such that a fan coupled to the second fan motor is rotated.
The fan control method of claim 1, wherein the preset value is determined in consideration of at least one of a load amount of the fan motors, a size of the fans, and a configuration of the air purifier.
The fan control method of claim 1, wherein in the second fan motor driving process, the second fan motor is operated after a preset period of time has elapsed from the initiation of the operation of the first fan motor.
The fan control method of claim 1, wherein, when the second operating speed is higher than the first operating speed, the second fan motor driving process is performed first, and the first fan motor driving process is then performed after a preset period of time has elapsed.
The fan control method of claim 3, wherein the preset period of time is determined in consideration of at least one of an inductance characteristic, a driving voltage, and a load amount of the fan motors.
A fan control method of an air purifier, comprising:

an operating mode determining process of determining an operating strength of the air purifier;

an operating speed setting process of setting a first operating speed and a second operating speed as operating speeds of a plurality of fan motors provided in the air purifier, wherein the first operating speed corresponds to the operating strength, and the second operating speed is determined by changing the first operating speed by a preset value; and

a driving process of operating the fan motors at the set operating speed and rotating the fans coupled to the fan motors.
The fan control method of claim 6, wherein the preset value is determined in consideration of at least one of a load amount of the fan motors, a size of the fans, and a configuration of the air purifier.
The fan control method of claim 6, wherein the driving process comprises:

a first fan motor operating process of operating a first fan motor rotating at the first operating speed; and

a second fan motor operating process of operating a second fan motor rotating at the second operating speed after a preset period of time has elapsed.
The fan control method of claim 8, wherein the preset period of time is determined in consideration of at least one of an inductance characteristic, a driving voltage, and a load amount of the fan motors.
The fan control method of claim 6, wherein, when the second operating speed is higher than the first operating speed, the driving process comprises:

a second fan motor operating process of operating a second fan motor rotating at the second operating speed; and

a first fan motor operating process of operating a first fan motor rotating at the first operating speed after a preset period of time has elapsed.
A fan control method of an air purifier, comprising:

a stopping determining process of determining fan motors to be stopped among a plurality of fan motors; and

a first fan motor stopping process of stopping any one of the fan motors to be stopped; and

when the number of the fan motors to be stopped is two or more, a second fan motor stopping process of stopping another one of the fan motors to be stopped, after a preset period of time has elapsed from the initiation of the stopping of the first motor.
The fan control method of claim 11, wherein the second fan motor stopping process is performed repetitively until the fan motors to be stopped are all stopped.
The fan control method of claim 11, wherein the preset period of time is determined in consideration of at least one of an inductance characteristic, a driving voltage, and a load amount of the fan motors.
An air purifier, comprising:

a plurality of fan motors configured to operate at operating speeds set according to a control signal;

a plurality of fans coupled to the fan motors to rotate to form air flow; and

a controller configured to set the operating speeds for the plurality of fan motors and transmit the control signal corresponding to the operating speeds to the fan motors.
The air purifier of claim 14, wherein the controller receives an operating strength of the air purifier and sets a first operating speed and a second operating speed as the operating speeds of the plurality of fan motors, wherein the first operating speed corresponds to the received operating strength, and the second operating speed is determined by changing the first operating speed by a preset value.
The air purifier of claim 15, wherein the controller first operates the fan motors set to the first operating speed, and then operates the fan motors set to the second operating speed after a preset period of time has elapsed.