Air purifier

Abstract

An air purifier comprising a removable filter medium, an ion generator comprising an emitting electrode and a receiving electrode, and an airflow generator, wherein the ion generator is arranged such that the ion emitting electrode is at most 20 cm from the removable filter medium, and when a suitable voltage is provided to the ion generator, the filter medium is bathed in an ion cloud.

Description

TECHNICAL FIELD

[0001] The present invention relates to an improved air purifier. BACKGROUND

[0002] CN 105 823 131 discloses a fresh air purification combined system for 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 independently arranged and fixed at different positions. The air purifier comprises a removable filter medium, an ion generator comprising an emitting electrode and a receiving electrode, and an airflow generator, wherein the ion generator is arranged such that the ion emitting electrode is at most 20 cm away from the removable filter medium, and when a proper voltage is provided to the ion generator in a room, the filter medium is bathed in an ion cloud, thus the indoor air quality can be controlled by the combination. According to the fresh air purification combined system for teaching area, by the combination of the constant-oxygen air purifier and the purification type fresh air ventilator, a constant-purity, constant-oxygen, energy-saving, green ecological classroom can be created, providing a safe and clean learning environment for students.

[0003] US 2002 141 131 discloses an improved air ion generator apparatus comprising an air inlet, a high voltage source, an electrode electrically connected to the high voltage source to generate ions, and an air outlet. An air mover is provided for flowing air into the air ion generator through the air inlet and out of the air ion generator through the air outlet. A small aperture filter comprising an electrically conductive material is electrically connected to at least one of the voltage source and ground. The filter is disposed 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 passes through the filter. In a preferred embodiment, the filter comprises a metal mesh or screen.

[0004] US 2007 034 082 discloses an air purifier comprising an ionizing assembly operative to charge particulate material in an air stream passing through the purifier. The charged particulate material is attracted and retained by a filter element disposed downstream of the ionizing assembly and having an opposite charge to the charged particulate material. Purified air passing through the filter is directed out of the device, optionally in combination with a scent added to the purified air stream. The ionizing assembly is formed with a grounding member disposed adjacent the ionizing member to hold electrons generated by the ionizing assembly within the purifier, thus preventing electrostatic discharge from occurring outside the purifier. The air stream is directed through the purifier in an angular and substantially laminar manner by a fan, such that the efficiency of the purifier is increased.

[0005] WO 2018 / 058716 discloses an integrated 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); sequentially provided in the housing (1) are a primary filter (3), a heat exchange core (4), an exhaust fan (5), a secondary filter (6), an ion cloud dust removal module, a blower (9) and a tertiary filter (10); the exhaust fan (5), the ion cloud dust removal module and the blower (9) are electrically connected to the power supply control device. The integrated device combines the functions of ventilation and air purification, plug and play, without installation and maintenance difficulties or structural problems of installing air ducts and damaging the room, with high negative ion generation, long delivery distance, strong dust removal and disinfection effect, and no ozone generated during operation, thus maintaining a healthy environment.

[0006] WO 2020 / 007549 discloses an ion generator for an air purification device, wherein the ion generator comprises a corona discharge tip and is capable of alternately generating a positive corona discharge and a negative corona discharge, wherein the ion generator 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 the first polarity to the second polarity, and wherein the switch is activated to switch polarity after a time period of 0.2 to 20 seconds. An air purification device comprising such an ion generator, a fan and a filter, and wherein the ion generator is arranged after the fan and before the filter in the direction of the air flow. The invention also relates to a vehicle comprising such an ion generator and a residence comprising such an air purification device. SUMMARY

[0007] Despite the prior art, there is still a need for improved air purifiers, especially air purifiers that are more hygienic during their entire working life.

[0008] Air purifiers work by filtering the ambient air through a filter. Thus, any substance in the air can in theory be captured by the filter. Although there are different types of filtering means, from particle filters to gas filters, an inevitable consequence of the function of air purifiers is that they also capture microorganisms caught in the air flow.

[0009] The main focus is on removing pollution from the ambient air and various sensors that indicate that particles are being removed are also a regular feature of air purifiers. It is therefore quite common for air purifiers to work in an automatic mode, the presence of particles thereby influencing the air flow speed through the device. Thus, it is possible and often desirable for the purifier to remain idle or standby mode when the air quality is good in order to save energy.

[0010] However, when air does not pass through the purifier, micro-organisms trapped by the filter can quickly grow and form biofilm, which can have a detrimental effect on the effective filter lifetime and also pose a health hazard to the user who is used to the domestic environment.

[0011] Thus, in a first aspect, there is provided an air purifier comprising a removable filter medium, an ion generator comprising an emitting electrode and a receiving electrode, and an airflow generator, wherein the ion generator is arranged such that the ion emitting electrode is at most 20 cm, preferably at most 15 cm, from the removable filter medium, and when an appropriate voltage is provided to the ion generator, the filter medium is bathed in an ion cloud.

[0012] The air purifier comprises an ion generator for generating an ion field during use. Preferably, the ion generator comprises a corona discharge tip (ion emitter) and a receiving electrode. When the corona discharge tip is subjected to an appropriate voltage, preferably from -10 kV to 10 kV, it generates an ion cloud between the tip and the receiving or ground electrode.

[0013] In order to generate an ion field that bathes the removable filter medium during use, the ion generator is located before the removable filter in the direction of the airflow and within a specified distance. If the ion generator is too far from the filter, the disinfecting effect is not sufficient to disinfect the filter without additional means. Preferably, the emitting electrode and the receiving electrode are arranged such that an ion cloud is generated in the direction towards the filter during use.

[0014] In addition, the air purifier can also comprise an external ion generator. If an ion generator is provided outside of the device, it is preferred to arrange it on top of the device. Placing the external ion generator on top of the device means that the domestic dust particles are ionized as they fall towards the ground after passing through the air, so they are more likely to aggregate as they become electrically charged. As they become more and more aggregated, they are more easily caught by the air circulation pattern generated by the device, thus being more easily filtered.

[0015] Preferably, the device comprises an internal ion generator and an external ion generator. The external ion generator promotes the aggregation of the domestic dust particles and the internal ion generator promotes the capture of the aggregated dust particles by the removable particulate filter. In both cases, ionization allows for a lower density filter medium and a low air speed (fan) speed.

[0016] Preferably, the airflow generator is housed within a volute, and more preferably, the ion generator is arranged at or near the outlet of the volute.

[0017] Preferably, the volute comprises an air flow outlet through which air flows from the air flow generator to the removable filter media, said outlet being defined by a perimeter and preferably comprising a receiving electrode and an associated emitting electrode, such that when the emitting electrode is subjected to an appropriate voltage, an ion cloud is formed between said receiving and emitting electrodes. The receiving electrode can thus be disposed around part or all of the perimeter of the outlet. In one preferred embodiment, the emitting electrode or corona discharge tip is disposed substantially centrally in the outlet, such that air flowing from the volute to the one or more removable filters is subjected to the ion cloud. Preferably, the receiving electrode is in the form of a cage, which extends away from the emitting electrode in the direction of air flow. More preferably, the receiving electrode is in the form of a meshed arrangement, and extends towards the filter. Such an extension can be hemispherical or part-cylindrical, such that the receiving electrode is downstream of the emitting electrode in the direction of air flow.

[0018] In a preferred embodiment, the air purifier comprises first and second removable filter media, which are angled relative to one another, such that there is an acute angle between said first and second media, said acute angle facing in the direction of air flow, and said purifier comprises an ion generator which, in use, generates an ion cloud between said first and second filter media. In such an embodiment, the filters are bathed in an ion field. Although, in general, the ion cloud is intended to ionise any particles carried in the air flow, we have surprisingly found that the ion cloud alone provides significant disinfection of the filter media and internal surfaces of the purifier. This is particularly useful when the purifier is in standby mode or switched off, whether for energy saving or simply because the user recognises that the air quality is sufficiently good. The ion generator uses significantly less energy than the air flow generator, so it is possible to maintain a sterile interior without having to switch on the fan.

[0019] Preferably, the emitting electrode is disposed substantially between the notional line between the proximal ends of said first and second filter media, said proximal ends facing 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 therebetween. In such an embodiment, it is preferred that the distal ends of the filter media are in contact or close to one another, such that they assume an inverted book-like arrangement, the tips pointing in the direction of air flow, the proximal ends of the filter media facing towards the air flow generator.

[0020] Preferably, the ion generator is disposed substantially between the proximal ends of the filter media, such that in use the filter media are bathed in an ion field. More preferably, the emitting electrode emits a stream of ions in the direction of air flow.

[0021] Preferably, the ion emitter is within 15 cm of the filter medium, more preferably within 10 cm, most preferably within 5 cm. The distance is calculated from the end point of the emitter tip and the closest part of the filter medium. If more than one filter is used, it is the closest. When more than one type of filter is used, it is preferred that the distance is in relation to the particulate filter.

[0022] In a second aspect, there is provided a method of disinfecting an inner surface of an air purifier or filter medium in an air purifier according to any of the preceding claims by subjecting the filter to an ion cloud.

[0023] More preferably, the method comprises:

[0024] (A) subjecting the inner surface or filter medium to an air flow;

[0025] (B) subjecting the inner surface or filter medium to an ion cloud;

[0026] wherein steps (A) and (B) are performed in any order or simultaneously.

[0027] In a preferred embodiment, the air flow generator and ionisation step are controlled automatically based on input from temperature and humidity sensors. In such an embodiment, the sensors sense the temperature and / or humidity on a continuous or intermittent basis and send the information back to the processor. The processor determines whether the conditions are conducive to microbial growth based on at least the temperature or the humidity. Preferably, the processor determines whether the conditions are conducive to microbial growth based on both the temperature and the humidity. More preferably, the processor also determines the likelihood of microbial growth based on parameters such as geographical location, time of day, week, month or season, or even pollution levels, as well as any specific circumstances occurring (such as a viral pandemic or a forest fire) and combinations of any of these.

[0028] For example, in South Asia, the wet season is typically defined by the monsoon and occurs in the summer. In contrast, the summer in Europe and North America is characterised by a drier climate. Similarly, the two hemispheres have different seasonal characteristics.

[0029] Preferably, the geographical location is determined by GPS or by the purifier WIFI functionality. It can also be provided by way of user input during a set-up process.

[0030] Temperature sensors are known in the art and are commercially available from Sensirion. Suitable examples of temperature sensors include the STS3x series.

[0031] Humidity sensors are known in the art and are commercially available from Sensirion. Suitable examples of humidity sensors include the SHT3x series.

[0032] In a preferred embodiment of the application, the purifier determines the likelihood of conditions being favourable to the growth of micro-organisms, and when such conditions are deemed to exist, it activates the air flow generator to destroy micro-organisms on the filter, or even those on the internal surfaces of the purifier. Preferably, this is done either according to a look-up table of the processor or by simple calculations based on temperature and humidity and knowledge of the location.

[0033] When the processor determines that conditions are favourable to the growth of micro-organisms, it either provides an indication by means 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 used, or it automatically activates the fan or impeller at a low speed as described herein and sufficient to prevent the growth of micro-organisms or to directly destroy micro-organisms.

[0034] Preferably, the purifier has a first mode in which the choices are: no action, in which case the conditions determined by the humidity sensor and the temperature sensor are such that no micro-organism growth or low micro-organism growth is expected; the option to alert the user by means of an electronic signal to a mobile device to warn that conditions are favourable to micro-organisms and allow the user to activate the fan; and a warning level, in which case the user is warned that micro-organism growth is possible and it is strongly recommended that the user activates the fan or impeller.

[0035] A second mode can operate similarly in that the indication made is determined by input from the temperature and humidity sensors, but when conditions are such that micro-organism growth is possible, the machine is automatically turned on, rather than an alert or alarm being issued.

[0036] The user can of course choose one of these two modes as appropriate.

[0037] We have surprisingly found that the ventilation required to kill micro-organisms is significantly lower than that required for air filtration, particularly when used in combination with subjecting the filter to a cloud of ions as described above.

[0038] Thus, in a preferred embodiment, the air purifier comprises means for controlling said air flow generator, a first air flow setting having an air filtration air flow speed and a second air flow setting related to the disinfection of the internal surfaces of the air purifier and / or the removable particle or gas filter. In practice, when the processor deems that micro-organism growth is possible, low ventilation and / or ionisation is activated. The fan can be activated to perform the low ventilation and / or the ion generator is activated. These actions are activated from a standby or idle state, independently of any action that can occur when the air purifier is used to filter air.

[0039] In a third aspect, there is provided an air purifier comprising a removable particle or gas filter, an airflow generator, means for controlling the airflow generator, a first airflow setting with an air filtration airflow speed and a second airflow setting, referred to as "low ventilation", related to the disinfection of the internal surfaces of the air purifier and / or the removable particle or gas filter.

[0040] In a fourth aspect, there is provided an air purifier comprising a "bacteria shield" setting which activates the ion generator without air flow and / or produces an air flow lower than that normally required for filtration, referred to as "low ventilation", for example about 1 cm / s -1 for disinfecting the internal surfaces or filter media in the purifier. The "bacteria shield" setting is a setting that allows the disinfection of the internal surfaces of the purifier, including the filter media, without the ordinary operation as a filtration means. For example, when in standby, the user can be alerted to environmental conditions in which microbial growth is particularly likely. Such an alert can be provided by the purifier, calculated by a processor that receives information from sensors, such as temperature and / or humidity sensors. The alert can be issued by an indicator on the device, or possibly the user can be alerted on their portable electronic device, such as a mobile phone or tablet.

[0041] Regardless of how they are alerted, the user can operate the setting that operates the ion generator without the airflow generator. This causes the internal surfaces of the device to be subjected to an ion cloud, so the rate of microbial growth is reduced or even reversed, with such microorganisms being destroyed.

[0042] Preferably, the ionization of the internal surfaces can be accompanied by simultaneous or sequential ventilation, preferably low ventilation as described above, to provide a synergistic disinfection effect.

[0043] The airflow speed measured at the removable filter is referred to in the art as the media speed. The media speed is the speed at which the air travels through the filter. The media speed must be perfectly controlled to ensure the capture of the maximum amount of particles. Too fast and many contaminants fly straight through without being filtered. Too slow and the purifier does not reach the farthest corners of your room fast enough to be of any use at all.

[0044] Preferably, the airflow speed (media speed) measured at the removable filter under the first "air filtration" setting is at least 1.5 cm / s -1 The measurement at the filter media is made from the spatial center point of the fan side of the filter media surface. In the case of more than one filter media, the one used for the ventilation measurement is the one closest to the airflow generator, thus the one that receives the ventilation first. The "air filtration" setting refers to a setting that delivers an airflow commensurate with the effect of conventional filtration, and is significantly higher than the "low ventilation setting", referred to as "low ventilation".

[0045] Preferably, the air flow velocity measured at the removable filter under the second,‘low ventilation’ setting is between 1% and 40% of the air flow velocity generated under the first setting.

[0046] More preferably, the air flow velocity measured at the removable filter under the second setting is between 0.1 and 1.2cms -1 .

[0047] Most preferably, the air flow velocity measured at the removable filter under the second setting is between 0.8 and 1.1cms -1 .

[0048] Preferably, the processor activates the air flow generator to generate the air flow for a period of time of between 1 second and 12 hours commensurate with disinfection of the internal surface of the air purifier and / or filter media.

[0049] In a fifth aspect, there is provided a method for disinfecting filter media or an internal surface of an air purifier, wherein the air purifier comprises a removable particulate or gas filter, an air flow generator, an ion generator, a device for controlling the air flow generator, a first air flow setting having an air filtration air flow velocity and a second air flow setting relating to disinfection of the internal surface of the air purifier and / or removable particulate or gas filter.

[0050] The purifier is powered by any suitable source of power, including internal sources such as batteries and external sources of power. The power is used to drive an electric motor, which in turn powers at least the air flow generator and the ion generator (if present).

[0051] Preferably, the filter media comprises at least one of carbon, activated carbon, nonwoven fabric, thermoplastic, thermoset, porous foam, fiberglass, paper, high loft spunbond web, low loft spunbond web, meltblown web, and or bimodal fiber diameter meltblown media.

[0052] Preferably, the filter media is a particulate filter or a gas filter.

[0053] Preferably, the removable particulate filter is a high efficiency particulate air (HEPA) filter. It should be understood that while the filter portion of an air purifier is an important part of its functionality, air purifiers are not typically manufactured with filters in place. They are actually always manufactured separately, most importantly, typically by a commercial enterprise that is different from the manufacturer of the air purifier itself. It is also typical for the filter manufacturer to manufacture filters for different air purifier models produced by different manufacturers. The particulate filter is to be contrasted with a pre-filter or any dust filter that is present. Pre-filters and dust filters are not considered HEPA filters because they do not exhibit the particulate capture capabilities of a HEPA filter. Preferably, the filter is pre-charged prior to application to the air purifier.

[0054] Pre-filters are filters with low air resistance that also function as a poke guard, preventing a user from accessing the volute or impeller assembly. Pre-filters are not intended to exhibit any primary role in air purification. They do not exhibit the air resistance or particulate entrainment capabilities of a dedicated particulate filter. Preferably, the pre-filter is not a HEPA filter.

[0055] The purifier of the present invention also includes a fan or impeller. The fan can be a bladeless fan, an axial fan, but preferably the fan is a radial fan. DETAILED DESCRIPTION

[0056] Embodiments of the present invention will now be described with reference to the following drawings, in which Figure 1 A cross-section of an embodiment is shown.

[0057] In particular, Figure 1 An air purifier (1) is shown, comprising a housing (2) and a fan (3) contained in a volute (4). The fan (3) is shown in simplified form, not attempting to depict its physical features or location. The volute (4) includes an outlet (5) through which air passes from the fan (3) to a filter (6). The filter (6) is attached at its top edge (7) to form a vertex. The volute outlet (5) also includes an ion emitter (9) and an ion receiver (8) for generating an ion field (not shown) that extends towards the filter (6).

[0058] In use, air passes into the purifier from the surrounding environment through an air inlet (10) that is fixed with a pre-filter (12) that acts as an initial filter to prevent large items carried in the air stream from entering and jamming the internal mechanics of the device, but also as a poke guard.

[0059] An air stream is then generated by the fan (3) and the air passes through the volute and to the filter (6) where it is cleaned.

[0060] Air then exits through outlet (13). Similarly, outlet (13) is also fixed with pre-filter (11).

[0061] Figure 2 is a schematic showing how the ion field generated by the ion generator arrangement would in use bathe the filter in a stream of ions. Shown are the volute (4) and the corona discharge tip (9) which when an appropriate voltage is applied to the tip (9) generates a stream of ions between the tip (9) and the receiving electrode (8).

[0062] The ion cloud (20) extends away from the tip (9) and bathes the filter (6) and provides a disinfecting effect.

[0063] Examples

[0064] The following experiment was designed to assess the effect of ionization alone on the viability of microorganisms on a substrate (in this case a particulate filter). The ion generator was subjected to -5kV to emit a stream of ions.

[0065] In this experiment, the airflow applied to the substrate was zero.

[0066] The microorganisms used were Staphylococcus aureus and Pseudomonas aeruginosa, with a biofilm formation incubation period of 5 days.

[0067] Results:

[0068] Distance (cm) 5 10 15 Log reduction of microorganisms 0.75 0.5 0.28

[0069] Conclusion:

[0070] The closer the ion generator emitter is to the substrate, the better the effect on the viability of the microorganisms.

Claims

1. An air purifier comprising a removable filter medium, an ionizer comprising an emitting electrode and a receiving electrode, and an air flow generator, wherein the air flow generator is housed within a volute, wherein the ionizer is disposed at or near the outlet on the volute, wherein the ionizer is disposed such that the ion emitting electrode is at most 15 cm from the removable filter medium, and when the ionizer is provided with an appropriate voltage, the filter medium is bathed in an ion cloud.

2. The air purifier of claim 1, wherein the volute comprises an air flow outlet through which air flows from the air flow generator to the removable filter medium, the outlet being defined by a perimeter and comprising a receiving electrode and an emitting electrode, such that when the emitting electrode is subjected to an appropriate voltage, an ion cloud is formed between the receiving electrode and the emitting electrode.

3. The air purifier of claim 1 or 2, comprising first and second removable filter media, the first and second filter media being angled with respect to each other such that there is an acute angle between the first and second filter media, the acute angle facing in the direction of air flow.

4. The air purifier of claim 3, wherein the ionizer comprises an emitting electrode and a receiving electrode, the emitting electrode being disposed substantially between an imaginary line between proximal ends of the first and second filter media, the proximal ends facing toward the air flow generator.

5. The air purifier of claim 1 or 2, wherein the air purifier comprises a removable filter medium, and the air flow rate generated at the removable filter medium is 0.1 to 1.2 cms -1 of the setting.

6. The air purifier of claim 1 or 2, comprising a bacteria shield arrangement that activates the ionizer in the absence of air flow for disinfecting interior surfaces or filter media in the purifier.

7. A method for disinfecting the interior surface of the air purifier or filter media in the air purifier according to any one of claims 1-6, comprising: (A) subjecting the interior surfaces or filter media to air flow; (B) subjecting the interior surfaces or filter media to an ion cloud; wherein steps (A) and (B) are in any order.

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