WO2021160736A1

WO2021160736A1 - Air purifier

Info

Publication number: WO2021160736A1
Application number: PCT/EP2021/053333
Authority: WO
Inventors: Lars Henrik DUNBERGER; Alagirisamy NETHAJI; Johan Daniel WENNERSTRÖM
Original assignee: Blueair Ab
Priority date: 2020-02-14
Filing date: 2021-02-11
Publication date: 2021-08-19
Also published as: CN113339923A; CN215929981U

Abstract

An air purifier comprising a removable filter medium, an ioniser comprising an emitting electrode and a receiving electrode, and air flow generator, wherein said ioniser is disposed such that the ion emitting electrode is up to 20 cm from the removable filter medium and that the filter medium is bathed in an ion cloud when a suitable voltage is provided to the ioniser.

Description

AIR PURIFIER

The present invention relates to an improved air purifier.

CN 105823 131 discloses a fresh air purification combined system for a teaching area. The fresh air purification combined system comprises an air treatment assembly. The air treatment assembly comprises a fresh air ventilator and an air purifier. The fresh air ventilator and the air purifier are arranged independently and fixed to different positions An air purifier comprising a removable filter medium, an ioniser comprising an emitting electrode and a receiving electrode, and airflow generator, wherein said ioniser is disposed such that the ion emitting electrode is up to 20 cm from the removable filter medium and that the filter medium is bathed in an ion cloud when a suitable voltage is provided to the ioniser in a room, and thus the indoor air quality can be controlled through combination. According to the fresh air purification combined system for the teaching area, through the combination of the constant-oxygen air purifier and the purification type fresh air ventilator, a constant-clean, constant-oxygen, energy-saving and green ecological classroom can be created, and a safe and clean study environment is provided for students.

US 2002 141 131 discloses an improved air ionizer apparatus includes an air inlet, a high voltage source, an electrode electrically connected to the high voltage source for generating ions and an air outlet. An air mover is provided for causing air to flow into the air ionizer through the air inlet and out of the air ionizer through the air outlet. A foraminous filter comprising an electrically conductive material is electrically coupled to at least one of a voltage source and ground. The filter is positioned over at least one of the air inlet, the air outlet and the electrode, such that air flowing into the air inlet, air flowing out of the air outlet or air flowing past the electrode flows through the filter. In a preferred embodiment, the filter comprises a metal grid or screen.

US 2007034082 discloses an air purifier including an ionizing assembly that operates to charge particulate material in an air flow passing through the purifier. The charged particulate material is attracted to and retained by a filter element disposed downstream of the ionization assembly and having an electrical charge opposite to the charged particulate material. The purified air passing through the filter is directed out of the device, optionally in conjunction with a fragrance that is added to the purified air flow. The ionizing assembly is formed with a ground member disposed adjacent the ionizing member to keep the electrons generated by the ionizing assembly within the purifier, and thus prevent static discharges from occurring outside of the purifier. The air flow is directed by a fan through the purifier in an angular and substantially laminar manner, such that the efficiency of the purifier is increased.

WO 2018/058716 discloses an all-in-one fresh air purifier, comprising a housing (1), an indoor return air inlet (21), an outdoor fresh air outlet (22), a fresh air delivery outlet (2), an indoor return air discharge outlet (12) and a power supply control device provided in the housing (1); provided in sequence in the housing (1) are a stage one filter (3), a heat exchange core (4), an exhaust fan (5), a stage two filter (6), an ion cloud dust removal module, an air blower (9) and a stage three filter (10); the exhaust fan (5), ion cloud dust removal module and air blower (9) are electrically connected to the power supply control device. The present all-in-one device combines ventilation and air purification functionality, is plug-and-play, presents no difficulties in installation and maintenance or structural problems of installing air pipes and damaging a room, has high negative ion generation, has a long conveying distance, has strong dust removal and disinfection effects, and furthermore does not generate ozone during operation, maintaining a healthy environment.

WO 2020/007549 discloses an ioniser for an air purifying device wherein the ioniser comprises a corona discharge tip and is capable of alternately generating positive corona discharge and a negative corona discharge, wherein the ioniser comprises a voltage source, a switch for switching from a first polarity to a second polarity or vice versa during use and a timer for timing the time interval between switching from a first polarity to a second polarity and wherein the switch is activated to switch the polarity after a period of from 0.2 to 20 seconds. Air purifying device comprising such an ioniser, a fan and a filter and wherein the ioniser is disposed after the fan and before the filter in an air flow direction. The invention also relates to a vehicle comprising such an ioniser and a dwelling comprising such an air purifying device.

Despite the prior art there remains a need for improved air purifiers, in particular air purifiers which are more hygienic throughout their working life.

Air purifiers work by filtering ambient air through a filter. Accordingly, anything in the air is in theory capturable by the filter. While there are different types of filtration means, from particulate filter to gas filter, it is a necessary consequence of the functioning of an air purifier that they also capture microbes caught in the air flow.

It is also a routine feature of air purifiers that the main focus is removing pollution from the ambient air and various sensors which indicate that particulates are being removed exist. Consequentially, it also is quite routine for an air purifier to work in an automatic mode whereby the presence of particulates influences the air flow speed through the device. Thus, when the air quality is good, it is possible and often desirable that the purifier is maintained in idle or stand-by mode to preserve energy.

However, when air is not passing through the purifier micro-organisms caught by the filter are able to grow quickly and form biofilms which can have a deleterious effect on effective filter life span and also cause a health hazard to the users who habit the domestic setting.

Accordingly, and in a first aspect there is provided an air purifier comprising a removable filter medium, an ioniser comprising an emitting electrode and a receiving electrode, and airflow generator, wherein said ioniser is disposed such that the ion emitting electrode is up to 20 cm, preferably 15 cm from the removable filter medium and that the filter medium is bathed in an ion cloud when a suitable voltage is provided to the ioniser.

The air purifier comprises an ioniser for generating the ion filed during use. Preferably, the ioniser comprises a corona discharge tip (ion emitter) and a receiving electrode. When the corona discharge tip is subjected to an appropriate electric voltage (preferably from -10kV to 10kV) it generates an ion cloud between the tip and the receiving or ground electrode.

In order to generate an ion filed which bathes the removable filter medium during use the ioniser is located before the removable filter in an airflow direction and within the specified distance. If the ioniser is too far from the filter the sterilisation effect is not sufficient to sterilise the filter without additional means. Preferably, the emitting electrode and receiving electrode are disposed such that the ion cloud is generated in a direction towards the filter during use.

In addition, the air purifier may also comprise an external ioniser. Where there is an ioniser disposed on the exterior of said device it is preferred that it is disposed at the top of the device. Locating the external ioniser at the top of the device means that domestic dust particles are ionised as they fall through the air towards the ground and are therefore more likely to aggregate as they become charged. As they become more aggregated they are more easily caught up in the air circulation pattern created by the device and so more easily filtered.

Preferably, the device comprises an interior ioniser and an exterior ioniser. The exterior ioniser facilitating aggregation of domestic dust particles and the interior ioniser facilitating capture of the aggregated dust particles by the removable particulate filter. In both instances the ionisation permits less dense filtration media and low air speed (fan) speeds. Preferably, the air flow generator is housed within a volute and more preferably, said ioniser is disposed at or near an outlet on the volute.

Preferably, the volute comprises an air flow outlet through which air flows from the air flow generator towards the removable filter medium, said outlet being defined by a perimeter and preferably comprising a receiving electrode and an associated emitting electrode such that between said receiving and emitting electrode there is formed an ion cloud when emitting electrode is subjected to an appropriate voltage. The receiving electrode may thus be disposed around a portion or all of the perimeter of the outlet. In a preferred embodiment the emitting electrode or corona discharge tip is disposed substantially centrally in the outlet such that air flowing from the volute and towards the removable filter or filters is subjected to an ion cloud. Preferably, the receiving electrode is in the form of a cage which extends away from the emitting electrode in an air flow direction. More preferably, the receiving electrode is in the form of a reticulated arrangement and which extends towards the filter. Such extension may present a hemispherical or partial cylindrical shape such that the receiving electrode is downstream in an airflow direction from the emitting electrode.

In a preferred embodiment, the air purifier comprises a first and second removable filter medium angled with respect to one another such that there exists an acute angle between said first and second media, said acute angle facing an air flow direction, and said purifier comprising an ioniser which during use generates an ion cloud between said first and second filter media. In such an embodiment the filters are bathed in an ion filed. While in ordinary circumstances the ion cloud is intended to ionise any particles entrained within the air flow we have surprisingly found that the ion cloud alone provides significant sterilisation of the filter media and internal surfaces of the purifier. This is particularly useful when the purifier is in stand-by mode or turned off whether to conserve energy or merely because the user believes that the air quality is sufficiently good. The ioniser uses considerably less energy than the air flow generator and so it is thus possible to maintain sterile conditions internally without having to turn on the fan.

Preferably, the emitting electrode is disposed substantially between an imaginary line between a proximal end of said first and second filter medium, said proximal ends being towards the air flow generator. In such an embodiment the air purifier comprises a pair of filter media angled relative to one another such that they form an acute angle between them. In such an embodiment it is preferred that the apex ends of the filter media are touching or are close to one another so that they present an inverted book arrangement with the tip pointing in an air flow direction and the proximal ends of the filter media facing towards the air flow generator. Preferably, the ioniser is disposed substantially between the proximal ends of the filter media such that the filter media are bathed in an ion filed in use. More preferably, the emitting electrode emits an ion stream in an air flow direction.

Preferably, the ion emitter is within 15 cm of the filter medium, more preferably within 10 cm and most preferably within 5 cm. This distance is calculated from the end point of the emitter tip and the nearest part of the filter media. If more than one filter is used it is the closest. Where more than one type of filter is used it is preferred that the distance relates to the particle filter.

In a second aspect there is provided a method for sterilising an internal surface of an air purifier or a filter media in an air purifier according to any preceding claim by subjecting said filters) to an ion cloud.

More preferably, the method comprises:

(A) subjecting said internal surface or filter media to an airflow;

(B) subjecting said internal surface or filter media to an ion cloud; where steps (A) and (B) are in any order or are simultaneously executed.

In a preferred embodiment the air flow generator and ionisation steps are controlled automatically based on input from a temperature and humidity sensor. In such an embodiment the sensors sense the temperature and/or humidity on a continuous or intermittent basis and send information back to a processor. The processor determines whether the conditions are conducive to micro-organism growth based on at least temperature or humidity. Preferably, the processor determines whether the conditions are conducive to micro-organism growth based on temperature and humidity. More preferably, the processor determines the likelihood of micro-organism growth additionally based on parameters such as geographical location, time of the day, week, month or season or even the pollution levels as well as any specific conditions that occur, for example virus pandemics or bush fires, and combinations of any of these.

For example, in South Asia, the wet seasons are typically defined by the monsoon and occurs in the summer. In contrast the summer in Europe and North America is characterised by drier weather. Similarly, the hemispheres have different seasonal characteristics. Preferably, the geographical location is determined by GPS or through the purifiers WIFI capability.

It may also be provided by way of user input during a set-up process.

Temperature sensors are known in the art and are commercially available from Sensirion. Suitable examples of temperature sensors include STS3x series.

Humidity sensors are known in the art and are commercially available from Sensirion. Suitable examples of humidity sensors include SHT3x series.

In preferred embodiments of the invention the purifier ascertains the likelihood of conditions conducive to micro-organism growth and when such conditions are deemed to exist it actuates the airflow generator to destroy the microbes on the filter, or even those on the internal surfaces of the purifier. Preferably, this done with reference to a look-up table by the processor or by way of simple calculation based on temperature and humidity and with respect to location.

When the processor determines that the conditions are conducive to micro-organism growth it either provides an indication, for example by way of a visual or audible signal, or electronically to a remote device such as a mobile phone so that the user is notified that the air flow generator should be employed, or it automatically actuates the fan or impeller at a low speed as described herein and which is sufficient to prevent micro-organism growth or to directly destroy the micro-organisms.

Preferably, the purifier has a first mode in which the choices are either: no action, where the conditions determined by the humidity sensor and temperature sensor are such that no or low micro-organisms growth is anticipated; an alert by way of an electronic signal to a mobile device to alert the user that conditions are favourable to micro-organisms and permitting the option for the user to actuate the fan; and a warning level where the user is warned that micro-organism growth is likely and strongly recommending to the user to actuate the fan or impeller.

A second mode may operate similarly in that indications are made determined by the input from the temperature and humidity sensors but instead of a warning or an alert, the machine is automatically turned on when conditions are such that micro-organism growth is likely.

The user of course may select one of these two modes where appropriate. We have surprisingly found that the air draft required to kill micro-organisms is significantly lower than that required for air filtration, particularly when used in combination with subjecting the filter to an ion cloud as described above.

Accordingly, in a preferred embodiment the air purifier comprises means for controlling said air flow generator, a first air flow setting with an air filtration air flow speed and a second air flow setting which correlates with sterilisation of an internal surface of the air purifier and/or removable particulate or gas filter. In practice, the low air draft and/or ionisation is activated when the processor deems that microbial growth is likely. The fan may be started to perform a low air draft and/or the ioniser is activated. These actions are activated from stand-by or idle and are not related to any actions which may occur when the air purifier is being used to filter the air.

In a third aspect there is provided an air purifier comprising a removable particulate or gas filter, an air flow generator, a means for controlling said air flow generator, a first air flow setting with an air filtration air flow speed and a second air flow setting known as ‘low air draft’ which correlates with sterilisation of an internal surface of the air purifier and/or removable particulate or gas filter.

In a fourth aspect there is provided an air purifier comprising a ‘germ shield’ setting which actuates an ioniser in the absence of an air flow, and/or generates an air flow (known as ‘low air draft’) which is below what is ordinarily required for filtration, for example at around 1 cms ¹, for sterilising an internal surface or filter medium in the purifier. Said ‘germ shield’ setting is a setting which permits sterilisation of an internal surface of said purifier including a filter medium in the absence of ordinary operation as a filtration means. For example, while in stand by the user may be alerted to environmental circumstances such that micro-organism growth is particularly likely. Such an alert may be provided by the purifier as calculated by a processor which receives information from sensors such as temperature and/or humidity sensors. Said alert may be through an indicator on the device or perhaps the user may be alerted on their portable electronic device such as a mobile phone or tablet.

However they are alerted, the user may operate a setting which operates the ioniser in the absence of the airflow generator. This results in the internal surfaces of the device being subjected to an ion cloud and thus the micro-organism growth rate is reduced or even reversed in that such microorganisms are destroyed. Preferably, the ionisation of said internal surfaces may be accompanied with a simultaneous or sequential air draft, preferably a low air draft as described above in order to provide a synergistic sterilisation effect.

The air flow speed measured at the removable filter is known in the art as the media velocity. Media velocity is the velocity at which the air travels through the filter. Media velocity has to be controlled perfectly to ensure that the maximum amount of particles are trapped. Too fast and many of the pollutants fly straight through unfiltered. Too slow and the purifier is not reaching the farthest comers of your room quickly enough to be of any use at all.

Preferably, the air flow speed (media velocity) measured at the removable filter at the first, ‘air filtration’ setting is at least 1.5 cms¹. The measurement at the filter medium is taken from the spatial centre point on the fan side of the filter media surface. Where there is more than one filter medium, the one taken for the air draft measurement is the one which is closest to the air flow generator and so receives the air draft first. By ‘air filtration’ setting is meant a setting which delivers and air flow commensurate with regular filtration efficacy and is significantly higher than what is termed ‘low air draft setting’.

Preferably, the air flow speed measured at the removable filter at the second ‘low air draft’ setting is from 1 to 40% the airflow speed generated at the first setting.

More preferably, the air flow speed measured at the removable filter at the second setting is from 0.1 to 1.2 cms¹.

Most preferably, the air flow speed measured at the removable filter at the second setting is from 0.8 to 1.1 cms¹.

Preferably, the processor actuates the air flow generator to generate an air flow commensurate with sterilisation of an internal surface of the air purifier and/or a filter media for a period of from 1 second to 12 hours.

In a fifth aspect there is provided a method for sterilising a filter media or internal surface of an air purifier wherein said air purifier comprises a removable particulate or gas filter, an air flow generator, an ioniser, a means for controlling said air flow generator, a first air flow setting with an air filtration air flow speed and a second air flow setting which correlates with sterilisation of an internal surface of the air purifier and/or removable particulate or gas filter. The purifier is powered by any suitable power source including internal sources, e.g. batteries, and external power sources. The power is used to drive a motor which in turn powers at least the air flow generator and the ioniser where present.

Preferably, the filter media comprises at least one of carbon, activated carbon, a non-woven, a thermoplastic, a thermosetting material, a porous foam, fibreglass, paper, a high loft spunbound web, a low loft spunbound web, a meltblown web and or a bi-modal fiber diameter meltblown media.

Preferably, the filter media is either a particulate filter or a gas filter.

Preferably, the removable particulate filter is a High Efficiency Particulate Air (HEPA) filter. It is to be understood that while the filter part of an air purifier is a vital part of its function, air purifiers are not commonly manufactured with a filter in place. They are practically always manufactured separately and most importantly often by a different commercial enterprise than of the manufacturer of the air purifier itself. It is also typical for a manufacturer of filters to manufacture filters for different air purifier models made by different manufacturers. The particulate filter is to be contrasted with the pre-filter or any dust filter which is present. Pre-filters and dust filters are not considered HEPA filters as they do not have the particulate capturing capability exhibited by HEPA filters. Preferably, the filter is precharged before application to the air purifier.

Pre-filters are filters which have a low air resistance and also function as a poke guard, preventing the user from touching the volute or impeller assembly. The pre-filters are not intended to exhibit any major effect in the context of air purification. They do not have the air resistance or particle entrainment capability of dedicated particulate filters. Preferably the pre-filter is not a HEPA filter.

The purifier of the inventions also comprises a fan or impeller. The fan may be a bladeless fan, an axial fan but it is preferred that the fan is a radial fan.

Embodiments of the invention will now be described with reference to the following in which figure 1 shows a cross section of an embodiment.

In detail, figure 1 shows an air purifier (1) comprising a housing (2) and a fan (3) contained in a volute (4). The fan (3) is shown in simplified form with no attempt made to describe its physical characteristics or placement. The volute (4) comprises an outlet (5) through which air is passed from the fan (3) to the filters (6). The filters (6) are connected at their top edges (7) to form an apex. The volute outlet (5) also comprises an ion emitter (9) and an ion receiver (8) for generating an ion filed (not shown) which extends towards the filters (6).

In use, air passes from ambient into the purifier through air inlets (10) which are secured with prefilters (12) which act as an initial filter preventing large items entrained in the air flow from entering and blocking the internal mechanics of the device but also acting as a poke guard.

An air flow is then generated by the fan (3) and the air passes through the volute and towards the filters (6) where it is cleaned.

The air then passes out through the outlets (13). Similarly, the outlets (13) are also secured with a pre-filter (11).

Figure 2 is a schematic showing how the ion filed generated by the ioniser arrangement bathes the filters in an ion stream in use. Shown is the volute (4) and a corona discharge tip (9) which generates an ion stream between the tip (9) and the receiving electrodes (8) when an appropriate voltage is applied to the tip (9).

The ion cloud (20) extends away from the tip (9) and bathes the filters (6) and provides a sterilisation effect.

EXAMPLE

The following experiment sets out to assess the impact of ionisation alone on micro-organism viability on a substrate, in this case a particulate filter. The ioniser was subjected to -5kV in order to emit an ion stream.

The air flow applied to the substrate in this experiment was zero.

The micro-organisms used were Staphylococcus aureus and Pseudomonas aeruginosa and the incubation period to generate the biofilm was 5 days. Results:

Conclusion: The closer the ioniser emitter to the substrate the better the impact on micro-organism viability.

Claims

1. An air purifier comprising a removable filter medium, an ioniser comprising an emitting electrode and a receiving electrode, and air flow generator, wherein said ioniser is disposed such that the ion emitting electrode is up to 20 cm from the removable filter medium and that the filter medium is bathed in an ion cloud when a suitable voltage is provided to the ioniser.

2. An air purifier according to claim 1 wherein said air flow generator is housed within a volute.

3. An air purifier according to claim 2 and wherein said ioniser is disposed at or near an outlet on the volute.

4. An air purifier according to claim 2 or 3 wherein the volute comprises an air flow outlet through which air flows from the air flow generator towards the removable filter medium, said outlet being defined by a perimeter and comprising a receiving electrode and an emitting electrode such that between said receiving and emitting electrode there is formed an ion cloud when emitting electrode is subjected to an appropriate voltage.

5. An air purifier according to any preceding claim comprising a first and second removable filter medium angled with respect to one another such that there exists an acute angle between said first and second media, said acute angle facing an air flow direction.

6. An air purifier according to claim 5 and wherein the ioniser comprises an emitting electrode and a receiving electrode, said emitting electrode disposed substantially between an imaginary line between a proximal end of said first and second filter medium, said proximal ends being towards the airflow generator.

7. A method for sterilising an internal surface of an air purifier or a filter media in an air purifier according to any preceding claim by:

(A) subjecting said internal surface or filter media to an airflow;

(B) subjecting said internal surface or filter media to an ion cloud; where steps (A) and (B) are in any order.

8. An air purifier according to any preceding claim wherein the air purifier comprises removable filter media and a setting which generates an air flow speed measured at the removable filter media is from 0.1 to 1.2 cms ¹.

9. An air purifier comprising a removable particulate or gas filter, an air flow generator, a means for controlling said air flow generator, a first air flow setting with an air filtration air flow speed and a second air flow setting which correlates with sterilisation of an internal surface of the air purifier and/or removable particulate or gas filter.

10. An air purifier according to any preceding claim comprising a germ shield setting which an ioniser in the absence of an air flow for sterilising an internal surface or filter medium in the purifier.