Air purifiers

Abstract

An air purifier comprising a removable particulate or gas filter, an airflow generator, means for controlling the airflow generator, a first airflow setting having an air filtering airflow velocity, and a second airflow setting correlated with sterilization of the air purifier's internal surface and / or the removable particulate or gas filter. A method for sterilizing the internal surface of the air purifier of any preceding claim by generating an airflow correlated with the second airflow setting. A method for sterilizing the internal surface of the air purifier of any preceding claim by generating an airflow correlated with the second airflow setting. A method for sterilizing the removable filter in the air purifier of any preceding claim by generating an airflow correlated with the second airflow setting. A method for preventing microbial growth on the air purifier's internal surface or removable filter by activating the airflow generator.

Description

[Technical field]

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

[0002] US 2007 034 082 discloses an air purifier including an ionizing assembly that operates to charge particulate material in an airflow 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. The purified air passing through the filter is directed out of the device, optionally together with a fragrance that is added to the purified airflow. The ionizing assembly is formed with a grounding member disposed adjacent to the ionizing member to retain electrons generated by the ionizing assembly within the purifier, thus preventing electrostatic discharge from occurring outside the purifier. The airflow is directed through the purifier in an angled and substantially laminar manner by a fan such that the efficiency of the purifier is increased.

[0003] US 2002 141 131 discloses an improved air ionizer device including 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 moving air into the air ionizer through the air inlet and out of the air ionizer through the air outlet. A perforated filter including a conductive material is electrically coupled to at least one of the 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.

[0004] 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 exhaust outlet (12), and a power supply control device arranged in the housing (1), in which a first stage filter (3), a heat exchange core (4), an exhaust fan (5), a second stage filter (6), an ion cloud dust removal module, a blower (9), and a third stage filter (10) are arranged in that order, and the exhaust fan (5), the ion cloud dust removal module, and the blower (9) are electrically connected to the power supply control device. This integrated device combines ventilation function and air purification function, is plug-and-play, does not bring difficulties in installation and maintenance or bring about the structural problem of installing air pipes and damaging the room, has a high negative ion generation rate, has a long transport distance, has strong dust removal and disinfection effect, and moreover, does not produce ozone during operation, maintaining a healthy environment.

[0005] CN 105 823 131 discloses a fresh air purification complex system with a teaching scope. The fresh air purification complex system includes an air treatment assembly. The air treatment assembly includes a fresh air ventilator and an air purifier. The fresh air ventilator and the air purifier are independently arranged and fixed at different positions in a room, so that they can be combined to control the indoor air quality. According to the fresh air purification complex system with a teaching scope, the combination of the constant oxygen air purifier and the clean fresh air ventilator can create a constantly clean, constant oxygen, energy-saving, and green eco-friendly classroom, providing a safe and clean learning environment for students.

[0006] Despite the existence of the prior art, there remains a need for improved air cleaners, particularly air cleaners that are more hygienic throughout their working life.

[0007] Air purifiers work by filtering the surrounding air through a filter. Thus, anything in the air can theoretically be captured by the filter. There are various types of filtering means, from particulate filters to gas filters, but it is an inevitable consequence of the function of an air purifier that it also captures microorganisms trapped in the air stream.

[0008] It is also a common feature of air purifiers that their main focus is to remove pollution from the ambient air, and there are various sensors that indicate that particulates are being removed. As a result, it is also very common for air purifiers to operate in automatic mode, with the presence of particulates affecting the airflow rate through the device. It is therefore possible, and often desirable, to keep the purifier in idle or standby mode to conserve energy when air quality is good. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] US 2007 034 082 [Patent Document 2] US 2002 141 131 [Patent Document 3] WO 2018 / 058716 [Patent Document 4] CN 105 823 131 Summary of the Invention

[0010] However, if the air is not passed through the purifier, microorganisms captured by the filter can rapidly multiply and form biofilms, which can adversely affect the effective filter lifespan and pose a potential health hazard to users in this home environment.

[0011] Thus, in a first aspect, the present invention relates to an air purifier comprising a removable particulate or gas filter, an airflow generator, means for controlling said airflow generator, a first airflow setting having an air filtered airflow velocity, and a second airflow setting correlated with sterilization of an internal surface of the air purifier and / or the removable particulate or gas filter.

[0012] The inventors have surprisingly found that moderate airflow rates can prevent microbial growth and dramatically reduce the prevalence of live microorganisms blown into the ambient air and released into the environment during filter changes.

[0013] Such microorganisms include gram positive bacteria, gram negative bacteria, spores, molds and fungi, and any viruses present alone in the ambient air or carried by any of these.

[0014] The inventors have surprisingly found that by providing a low airflow, the viability of microorganisms on the inner surfaces of an air purifier, particularly on the filter media, can be dramatically reduced. While the purifier is operating, there is no increased risk of microorganisms growing and multiplying on the filter. However, when the purifier is in idle or standby mode, microorganisms do grow. The airflow velocity required to reduce the viability of microorganisms is significantly lower than the velocity required to filter the air, and therefore can be achieved at a much lower energy consumption level. Furthermore, the low air draft required to significantly affect the viability of microorganisms is much more effective than simple air drying.

[0015] In a preferred embodiment of the invention, the purifier checks for possible conditions conducive to microbial growth and, if such conditions are deemed to exist, activates the airflow generator to destroy the microorganisms on the filter or even inside the purifier.

[0016] The inventors have surprisingly found that the airflow required to kill microorganisms is significantly lower than the airflow required for air filtration.Accordingly, in a preferred embodiment, the air purifier comprises a means for controlling said airflow generator, a first airflow setting having an air filtration airflow rate, and a second airflow setting that correlates with sterilization of the internal surface of the air purifier and / or a removable particulate or gas filter.

[0017] The airflow velocity measured with a removable filter is known in the art as the media velocity. The media velocity is the speed at which the air moves through the filter. The media velocity must be perfectly controlled to ensure that the maximum amount of particles are captured. If the velocity is too high, many of the contaminants will go straight through unfiltered. If the velocity is too low, the purifier will not reach the farthest corners of the room fast enough to be effective. It is also important to understand that the media velocity is not just the speed at which the air approaches the filter, but the speed at which the air passes through the filter. Therefore, this is an important distinction, as the speed at which the air approaches a pleated filter is significantly different than the speed at which the air passes through a pleated filter. The pleats in the filter have a large effect on the calculation. The particulate filters used in the present invention are preferably pleated.

[0018] Preferably, the air flow velocity (media velocity) measured at the removable filter in the first air filtration setting is at least 1.5 cms -1 Measurements on the filter media are taken from the spatial center point on the fan side of the filter media surface. If multiple filter media are present, the surface taken for the airflow measurement is the one closest to the airflow generator and therefore first to receive the airflow.

[0019] Preferably, the airflow velocity measured at the removable filter in the second setting is between 1 and 40% of the airflow velocity produced in the first setting.

[0020] Most preferably, the airflow velocity measured at the removable filter in the second setting is between 0.7 and 1.1 cms. -1 It is.

[0021] Preferably, the processor activates the airflow generator to generate an airflow consistent with sterilization of the internal surfaces and / or filter media of the air cleaner for a period of between 1 second and 10 hours.

[0022] Preferably, the air purifier comprises means for activating said second airflow setting, which may comprise a knob or switch that indicates to a user that a "sterilization mode" is selectable and that this is distinct from an air filtration mode.

[0023] In a preferred embodiment, the means for controlling the airflow generator is performed automatically, for example by a processor consulting a look-up table, based on input from the sensor. In such an embodiment, the sensor senses temperature and / or humidity continuously or intermittently and sends information back to the processor. The processor determines whether conditions are conducive to microbial growth based on at least the temperature or humidity. Preferably, the processor determines whether conditions are conducive to microbial growth based on temperature and humidity. More preferably, the processor determines the likelihood of microbial growth further based on parameters such as geographic location, time of day, week, month or season, or pollution levels, and any particular conditions occurring, such as a virus pandemic or bush fire, and any combination of these.

[0024] For example, in Asia, the wet season is typically defined by the monsoon, which occurs in the summer. In contrast, summer in Europe and North America is characterized by drier weather. Similarly, the hemispheres have different seasonal characteristics.

[0025] Preferably, the geographic location is determined by GPS or the purifier WIFI capabilities, which may also be provided by user input during the set-up process.

[0026] If the processor determines that conditions are conducive to microbial growth, it provides an indication, for example by a visual or audible signal or electronically to a remote device such as a cell phone, thereby informing the user that an airflow generator should be used, or automatically operates a fan or impeller at a slow speed as described herein, which is sufficient to prevent microbial growth or to directly destroy the microorganisms.

[0027] Preferably, the purifier has a first mode in which the options are either: no action where conditions determined by the humidity and temperature sensors are such that no or low microbial growth is expected; an alert via an electronic signal to the mobile device to alert the user that conditions are favorable for microorganisms and allow the user the option to activate the fan; and a warning level which alerts the user that microbial growth is likely and it is strongly recommended that the user activate the fan or impeller.

[0028] A second mode may operate similarly in that the instructions are determined by input from the temperature and humidity sensors, but instead of a warning or alert, the machine will automatically turn on when conditions are likely for microbial growth to occur.

[0029] Of course, the user may select one of these two modes as appropriate.

[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] Preferably, the air purifier comprises a timer for measuring the time since the last air filtration event. More preferably, the purifier comprises means for indicating to the user the time since the last operation. Said means for indicating may itself form part of the purifier, or alternatively may be an electronic signal to a portable electronic device, for example on a mobile phone, and an app can work in conjunction with the purifier to provide information on, for example, the air quality as well as the functionality of the purifier.

[0033] In a second aspect, there is provided a method for sterilizing an internal surface of an air cleaner described herein by generating an airflow that correlates with said second airflow setting.

[0034] In a third aspect, a method is provided for preventing microbial growth on an internal surface or removable filter of an air cleaner by automatically activating an airflow generator.

[0035] Preferably, the airflow generator is activated after a predetermined period of time since the last activation of said airflow generator. For example, after a period determined by either ambient conditions such as temperature and / or humidity, the purifier may be equipped with a processor capable of determining an appropriate period of time between uses, thereby limiting or reducing microbial growth inside the device, whether on or in the filter media or on the interior surfaces of the device. The period of time between uses may also depend on the geographic location, as discussed above.

[0036] The purifier is powered by any suitable power source, including an internal power source, e.g., a battery, and an external power source. The power is used to drive a motor, which powers at least the airflow generator and the ion generator, if present.

[0037] Preferably, the filter media comprises at least one of carbon, activated carbon, nonwoven fabric, thermoplastic material, thermoset material, porous foam, fiberglass, paper, high loft spunbond web, low loft spunbond web, meltblown web, and / or meltblown media having bimodal fiber diameter.

[0038] Preferably, the removable particulate filter is a high efficiency particulate air (HEPA) filter. It should be understood that air purifiers are not usually manufactured with filters in place, although the filter section of the air purifier is an important part of its function. They are in fact always manufactured separately, and most importantly, are often manufactured by a commercial company different from the manufacturer of the air purifier itself. It is also typical for a filter manufacturer to manufacture filters for different air purifier models made by different manufacturers. Particulate filters should be contrasted with pre-filters or any dust filters present. Pre-filters and dust filters are not considered HEPA filters, since they do not have the particulate capture capability exhibited by HEPA filters. Preferably, the filters are pre-charged before application to the air purifier.

[0039] Pre-filters are filters that have low air resistance and also act as poke guards to prevent the user from touching the volute or impeller assembly. Pre-filters are not intended to have a significant effect on air purification. They do not have the air resistance or particle entrainment capabilities of dedicated particulate filters. Preferably, pre-filters are not HEPA filters.

[0040] The purifier of the present invention also comprises a fan or impeller. The fan may be a bladeless fan, an axial fan, but is preferably a radial fan.

[0041] Preferably, the air purifier comprises an ion generator. Preferably, the ion generator comprises a corona discharge tip and a backing electrode. When the corona discharge tip is subjected to a suitable voltage, the corona discharge tip generates an ion cloud between the tip and the backing or ground electrode.

[0042] The ion generator may be located inside or outside the purifier. If the ion generator is located outside the device, it is preferably located on the top surface of the device. Locating an external ion generator on the top surface of the device means that household dust particles are more likely to agglomerate as they fall through the air towards the ground, becoming ionized and therefore electrically charged. As they become more agglomerated, they are more easily caught up in the air circulation pattern created by the device and therefore more easily filtered.

[0043] If the ion generator is located inside the device, it is preferably located in front of the removable particulate filter in the airflow direction.

[0044] Preferably, the device includes an internal ion generator that facilitates agglomeration of household dust particles and an external ion generator that facilitates capture of the agglomerated dust particles by a removable particulate filter. In both cases, ionization allows for a less dense filtration media and lower air (fan) speeds.

[0045] [Example 1] The following experiment is shown to evaluate the effect of low airflow alone on the viability of microorganisms on a substrate, in this case a particulate filter. No ionization of the substrate occurred.

[0046] The microorganisms used were Staphylococcus aureus and Pseudomonas aeruginosa and the incubation period for generating biofilms was 5 days.

[0047] [Table 1]

[0048] 0.018ms -1 Although the low airflow did not result in a decrease in microbial growth, it still resulted in some slowing of growth.

[0049] [Example 2] The air purifier has a particulate filter that is ionized and has a low airflow (1cms -1 ) for 10 hours with ionization for 2 hours, with the ionization step coming first.

[0050] Again, the ion generator was set at -5 kV and the test microorganisms (Staphylococcus aureus and Pseudomonas aeruginosa) were allowed to grow for 5 days prior to testing.

[0051] The control had a log microbial count of 6 and a test score of 2.5.

[0052] [Example 3] The air purifier is designed to have an ionized inner surface and low airflow (1cms -1 ) for 10 hours with ionization for 2 hours, with the ionization step coming first.

[0053] Again, the ion generator was set at -5 kV and the test microorganisms (Staphylococcus aureus and Pseudomonas aeruginosa) were allowed to grow for 5 days prior to testing.

[0054] The control showed 152 colonies of organisms giving a test score of 6.

Claims

1. 1. An air cleaner comprising a removable particulate or gas filter, an airflow generator, means for controlling said airflow generator, a first airflow setting having an air filtered airflow velocity, and a second airflow setting, said airflow velocity measured at a removable filter at said second airflow setting (second airflow velocity) being between 0.1 and 1.2 cms －１ and wherein the second airflow velocity prevents microbial growth on internal surfaces of the air cleaner and / or a removable particulate or gas filter, and the airflow velocity measured at the removable filter at the first setting is at least 1.5 cms −1 .

2. 10. The air purifier of claim 1, wherein the airflow velocity measured at the removable filter at the second setting is between 1 and 10% of the airflow velocity produced at the first setting.

3. 3. An air purifier according to claim 1 or 2, comprising a timer for measuring the period since the last air filtration event.

4. 4. The air purifier of claim 3, comprising means for activating the second airflow setting.

5. A method for preventing microbial growth on internal surfaces of an air purifier according to any one of claims 1 to 4 by generating an air flow that correlates with the second air flow setting.

6. A method for preventing microbial growth on a removable filter in an air purifier according to any one of claims 1 to 5 by generating an airflow that correlates with the second airflow setting.

7. A method for preventing microbial growth on an internal surface or a removable filter of an air purifier according to claim 3 or 4 by activating the airflow generator.

8. The method of claim 7 , wherein the airflow generator is activated a predetermined period of time after a last activation of the airflow generator.

Images