WO2021160683A1

WO2021160683A1 - Air purifier

Info

Publication number: WO2021160683A1
Application number: PCT/EP2021/053228
Authority: WO
Inventors: Lars Henrik DUNBERGER
Original assignee: Blueair Ab
Priority date: 2020-02-14
Filing date: 2021-02-10
Publication date: 2021-08-19
Also published as: WO2021160683A8; CN214949609U; CN113339924A

Abstract

An air purifier comprising a removable particulate filter, an air displacement means housed in a volute, a motor and an ioniser, the ioniser being disposed at a volute exit such that air passing from the volute is ionised as it exits the volute towards said removable particulate filter and wherein the ioniser comprises an emitting electrode and a receiving electrode and that the emitting electrode is disposed substantially centrally in the volute exit, and a method for removing bacteria, viruses and moulds from ambient air by filtering ambient air with such an air purifier.

Description

AIR PURIFIER

The present invention relates to an improved air purifier.

WO 2017/072393 (AirO OY) discloses a corona discharge needle which is used in a corona charger for electrically charging airborne particulates in the size range of 10 nm - 2500 nm. The needle comprises a sharp part and a spring-like part which fixes the needle to the support and provides electrical connection between the sharp part and support.

US 2005058582 (Paumier Carine) discloses an installation for heating/air conditioning the cabin of a motor vehicle, comprising a powered fan unit delivering a flow of air in an air distribution conduit in which at least one evaporator is disposed, an electrostatic filtration system is provided, comprising an ionising part and a collecting part, placed upstream of a plasma catalysis system comprising a plasma generating part.

JP2004358359 (Matsushita) discloses an electrostatic atomizer which can stabilize the quantity of atomization, can increase the quantity of atomization, and can minimize the generation of ozone and an air cleaner using the atomizer. In the electrostatic atomizer, a transportation part having water absorbency for transporting water from water storage part is provided. A counter electrode part which is arranged on the transportation direction side of the transportation part and faces the transportation part is provided. An application electrode which can apply voltage to water in a pathway ranging from the water storage part to the tip on the counter electrode side of the transportation part is provided. A voltage application part which applies a high voltage between the application electrode and the counter electrode part is provided. The counter electrode part is formed in the shape of an arc.

WO 2020/007549 (BlueairAB) 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. US 2018 169666 (Loreth Andrzej) discloses a device for cleaning of indoor air comprising capacitor precipitators (12a, 12b) each consisting of two electrode elements or two groups of electrode elements connected to the respective pole of a high voltage source, air transported fans (13a, 13b), at least one corona electrode (K1, K2) and at least one counter electrode (16a, 160, 16c), wherein said corona electrode (K1, K2) and said counter electrode (16a, 16b, 16c) are connected each to a pole of a high voltage source. The characteristics of the apparatus of the present invention is that it comprises two air flow ducts (L1 , L2) for the air to be cleaned, which air flow ducts (L1 , L2) are placed along an axial reference line (AA) at a distance (d) from each other in the direction of the axial reference line (AA), that each air flow duct (L1, L2) is associated with a capacitor precipitator (12a, 12b) and an air moving fan (13a, 13b), that at least one corona electrode (K1, K2) is provided in the space between the air flow ducts (L1 , L2), that at least one counter electrode (16a, 16 b; 16) is located adjacent to the air flow ducts (L1, L2) circumference, that the air flow direction through the one air flow duct (L1) is diametrically opposite the air flow direction through the second air flow duct (L2) and that the air to be cleaned is passed into the space between the air flow ducts (L1 , L2).

US 2016 102589 (Kim Hak Joon) discloses a vehicle air purifying apparatus. The vehicle air purifying apparatus includes: a charger configured to discharge positive (+) ions or negative (-) ions to charge particles included in harmful gas; a removable collecting electrode configured to have positive (+) or negative (-) polarity to allow the particles charged by the charger to be attached thereto; and a filter configured to filter harmful gas and have positive (+) or negative (-) polarity, and the filter is formed in a tubular shape having an empty space therein and the removable collecting electrode is inserted into the filter.

US 2011 100221 Wu Fu-Chi) discloses an air purifier including a vertically disposed housing provided with a wire gauze filter, electric fans and air filter elements. The electric fans draw outside air around the floor vertically into the bottom air intake port toward the top air output port of the housing so that the flow of air, when passed out of the air output port, flows upwards to a certain elevation and is then diffused and lowered in all directions around the housing. By means of the traction of the flow of air, the pressure difference of the convection of air between the low air pressure and the high air pressure at the bottom and top sides of the housing, high concentration of car waste gas, micro dust particles, hair dust, micro fibers and other harmful industrial odors that fall to the floor due to the effect of gravity or floating nearly above the floor are sucked into the inside of the housing by the low air pressure zone at the open bottom side of the housing and then removed by the filter elements.

Despite the prior art there remains a need for improved air purifiers. Accordingly, and in a first aspect there is provided an air purifier comprising a removable particulate filter, an air displacement means housed in a volute, a motor and an ioniser, the ioniser being disposed at a volute exit such that air passing from the volute is ionised as it exits the volute towards said removable particulate filter and wherein the ioniser comprises an emitting electrode and a receiving electrode and that the emitting electrode is disposed substantially centrally in the volute exit.

We have surprisingly found that improvements can be made by locating the ioniser at the exit to the volute. In particular, ionisation efficiency is improved as the ion distribution within the ion cloud is more homogeneous. Further, there is a reduction in ozone generation.

The air purifier comprises an ioniser for generating the ion cloud 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 cloud which bathes the removable filter medium during use the ioniser is preferably located before the removable filter in an air flow direction.

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 comprises a perimeter part and a reticulated part. In such an embodiment the reticulated part extends within the perimeter and provides a more uniform distribution of ions in the ion cloud. More preferably, the reticulated part extends from the perimeter part to form a substantially arched receiving electrode. In such an embodiment the reticulated part extends away from the general plane of the perimeter part to form the arch-like structure. In a most preferred embodiment the distance between the emitting electrode and any point on the reticulated part does not deviate from 30% of the average distance. Most preferably, the distance is substantially constant.

Preferably, the receiving electrode forms an arch or bridge-like arrangement whereby the ends are located near or on the perimeter of the volute exit and the middle part, between the two ends, extends away from the volute and towards the removable filters). In such an embodiment an in a side cross section, the receiving electrode would appear as an arc extending from the perimeter of the volute exit, towards the filter and back to the opposite side of the volute exit.

Preferably, the arched receiving electrode extends away from the volute and towards the removable particulate filter. In such an embodiment the ion cloud is dispersed towards the filter(s) and away from the volute. This improves the ionisation step in air filtration.

The reticulated receiving electrode has the additional benefit of acting as a poke guard for the volute.

Preferably, the air purifier comprises a pair of removable particulate filters disposed in an inverted V shape and facing the volute and ioniser.

In such an 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.

In a second aspect there is provided a method for removing airborne micro-organisms such as bacteria, viruses, moulds, or spores thereof from ambient air by filtering ambient air with an air purifier according to the first aspect.

Typical viruses include influenza, the cold virus and coronaviruses.

In a third 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 the first aspect 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 microorganism 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 air flow generator to destroy the microbes on the filter, or even those on the internal surfaces of the purifier.

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 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.

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 a fourth 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 which correlates with sterilisation of an internal surface of the air purifier and/or removable particulate or gas filter.

In a fifth 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 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 air flow generator. This results in the internal surfaces of the device being subjected to an ion filed 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. T oo fast and many of the pollutants fly straight through unfiltered. Too slow and the purifier is not reaching the farthest corners 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.

Preferably, the air flow speed measured at the removable filter at the second setting is from 1 to 40% the air flow 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 seventh 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 (14) for generating an ion cloud (not shown) which extends towards the filters (6). The ion receiver is in two parts: a perimeter (8) and a cage like structure (14) 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 view from the side and of a cut away purifier showing the housing (2) and an impeller (3) contained in a volute (4). The impeller (3) is shown in cross section. The volute (4) comprises an outlet (5) through which air is passed from the impeller (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 (14) for generating an ion cloud (not shown) which extends towards the filters (6).

In use, an air flow is then generated by the impeller (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).

Figures 3, 4 and 5 are of an ionising receiving electrode. Figure 3 is a plan view of a receiver showing its cage like structure. The electrode has a pair of end rods (31) which are spaced apart from one another by parallel rods (32). These end rods (31) and parallel rods (32) are crossed by orthogonally disposed cross rods (33) with the two outermost cross rods forming cross end rods (30).

The electrode is made from any suitable conducting material.

Figure 4 shows the same electrode in perspective view and shows the curved arrangement with each cross rod (33) and cross end rod (33) shaped to describe a curve. The parallel rods and end rods meanwhile are straight so the structure as a whole forms an arch. Figure 5 shows the same electrode as in figures 3 and 4 and is an end view.

Figure 6 is a schematic of a comparative device which has a ring-like receiving electrode (8) seen in figure 6 from the side and in figure 7 from above. The emitting electrode (5) emits corona discharge which forms an ion cloud in which particles are ionised as they pass from the fan (not shown) to the filters (not shown). The ion stream passes from the emitting electrode upwards before returning back towards the receiving electrode. In this arrangement the ion cloud is heterogenous meaning that ionisation performance is not uniform.

In contrast, in figure 8, the ioniser comprises a receiving electrode such as described in figures 4, 5 and 6. The ion cloud generated is uniform and so ionisation performance is improved.

Claims

1. An air purifier comprising a removable particulate filter, an air displacement means housed in a volute, a motor and an ioniser, the ioniser being disposed at a volute exit such that air passing from the volute is ionised as it exits the volute towards said removable particulate filter and wherein the ioniser comprises an emitting electrode and a receiving electrode and that the emitting electrode is disposed substantially centrally in the volute exit.

2. An air purifier according to claim 2 wherein the receiving electrode comprises a perimeter part and a reticulated part.

3. An air purifier according to claim 3 wherein the reticulated part extends from the perimeter part to form a substantially arched receiving electrode.

4. An air purifier according to claim 4 wherein the perimeter part of the receiving electrode is disposed at a perimeter of the volute exit.

5. An air purifier according to claim 4 or 5 wherein the arched receiving electrode extends away from the volute and towards the removable particulate filter.

6. An air purifier according to any preceding claim comprising a pair of removable particulate filters disposed in an inverted V shape and facing the volute and ioniser.

7. A method for removing bacteria from ambient air by filtering ambient air with an air purifier according to any of claims 1 to 7.

8. A method for removing viruses from ambient air by filtering ambient air with an air purifier according to any of claims 1 to 7.

9. A method for removing corona virus from ambient air by filtering ambient air with an air purifier according to any of claims 1 to 7.

10. A method for removing influenza virus from ambient air by filtering ambient air with an air purifier according to any of claims 1 to 7. ll. A method for removing mould or mould spores from ambient air by filtering ambient air with an air purifier according to any of claims 1 to 7.