NL2020193B1 - Filter system for filtering a flow, extractor hood comprising such filter, and method for filtering air - Google Patents

Abstract

The present invention relates to a filter system, extractor hood provided therewith and method for filtering air. The filter system comprises: a filter housing having a suction opening for inlet of an indrawn flow and an outlet for outlet of a filtered flow, with the filter housing defining an flow path for the indrawn air; a carbon filter that is provided in the flow path and is configured for filtering the indrawn air; and a plasma filter that is provided in the flow path downstream from the carbon filter and is configured for generating ozone and providing the ozone to the indrawn flow.

Description

Filter system for filtering a flow, extractor hood comprising such filter, and method for filtering air

The present invention relates to a filter system for filtering a flow, more specifically for filtering an air flow. Such filter systems can be used in kitchens for cooking facilities, production environments and hospitals, for example.

Known filter systems use a fan to draw in air through an inlet opening or a suction opening. The air is forced through one or more filters including a grid and/or carbon filters. The air is discharged to the environment or is recirculated. These filter systems are also referred to as passive filters.

Also known, are active filters including an electrostatic filter and/or a plasma filter generating ozone. Such filter system is described in NL 2009138, for example.

Conventional passive filters have a varying performance strongly depending on maintenance, for example. Active filters produce ozone and require additional energy.

The present invention has for its object to obviate or at least reduce one or more of the aforementioned problems and to provide an effective and efficient filter system.

The present invention provides for this purpose a filter system according to clause 1 for filtering a flow.

The filter system comprises a filter housing with an inlet opening or suction opening for the indrawn flow, such as an airflow in a kitchen facility. In the housing there are provided a carbon filter and a plasma filter. The carbon filter is preferably provided close to the inlet or directly in the inlet of the filter housing. Such filter is preferably easy to dismount from the housing to enable cleaning and/or a change of the filter.

Providing a plasma filter, with the plasma filter being capable of functioning as an ozone generator, achieves an additional air cleaning. The plasma filter generates ozone and/or radicals that react with contaminations, such as odours, in the indrawn air. Preferably, the ozone generator of the plasma filter is operatively connected to an ozone sensor. In practice, ozone is also referred to as plasma. For the purpose of this document ozone relates to ozone/plasma. According to the present invention the plasma filter is provided after the carbon filter such that ozone particles enter the flow path after the air has passed through the carbon filter. Surprisingly, this specific configuration of the carbon filter and the plasma filter that generates the ozone improves the cleaning effect without exhaust air leaving the filter system having too much ozone particles. Preferably, an ozone sensor is provided to monitor the actual ozone level. Surprisingly, the specific configuration of the present invention shows that the actual levels are below the safety limits. As a further effect this increases the lifespan of the carbon filter. Preferably, the plasma filter is embodied as a modular unit that can be attached to the filter housing. This provides the opportunity to use the filter system also without a plasma filter. Furthermore, such modular configuration enables easy maintenance and/or replacement of the unit.

Optionally, the filter housing also comprises an electrostatic filter. Such electrostatic filter preferably realizes a direct voltage of for instance 5 kV which is transmitted to a screen/gaze. Gaze includes screens, grids and similar elements. A first gaze or screen acts as a first electrode and a second gaze or screen acts as a second electrode. The electrodes are separated, preferably using a filling material to fill the gap between the two electrodes. Preferably, the filling material comprises glass fibre material. By providing a glass fibre material, an improved filtering of contaminations out of the indrawn air is achieved. In particular, contaminations are trapped in the glass fibre filter. The glass fibre material cooperates with the electrostatic filter such that an electric discharge eliminates the contaminations trapped in the glass fibre material. This provides additional filtering of the indrawn air.

In presently preferred embodiments of the invention the gazes or screens extend in a direction that is substantially perpendicular to the (average) air flow. A type of potential filter is hereby realized with which an electrostatic field is created. Contaminations, including particles such as smoke particles, fungi, odour particles, pollen, bacteria, moisture, viruses, fungi and so on, can be captured by means of such a filter and thereby removed from the indrawn air.

It has been found that in particular a combination of an electrostatic filter and a plasma filter achieves an effective cleaning due to the production and effective use of radical particles. These particles act on the cell walls and other parts of undesired particles/contaminations in the indrawn air. In presently preferred embodiments of the invention the plasma filter is positioned in the air flow before the electrostatic filter. Contaminations are first subjected to the plasma filter and thereafter to the electrostatic filter. It was shown that this provided an effective filtering of the indrawn air.

The filter system according to the invention further preferably comprises a controller that is proactively connected to a sensor. The sensor is configured for measuring the indrawn airflow, more specifically for measuring specific characteristics of the indrawn airflow including one or more of: air quantity, air speed, contamination including odours, etc. In one of the presently preferred embodiments of the invention the sensor comprises an ozone detector that is configured to measure the ozone level in the indrawn air. The sensor or sensors provide the measurement information to the controller that may decide to active or deactivate the filter system and/or to adjust the parameters or settings of the filter system. This improves the overall safety of the filter system and its environment. Furthermore, it enables the use of a filter system having a higher maximum capacity that can be controlled at the desired capacity taking into account the actual conditions. The ozone sensor/detector measures the ozone level in the exit air/exhaust air. As already mentioned, the specific configuration of the present invention shows that the actual levels are below the safety limits.

The controller typically activates the filters of the filter system in presence of an airflow. Therefore, the filters are activated only in case of an airflow. This reduces the energy requirements for the filter system. Furthermore, the controller may adjust frequencies and/or voltage levels of the electrostatic filter and/or plasma filter. This renders the climate system more effective and efficient as compared to conventional filter systems.

The one or more sensors can be provided in combination with the housing of the filter system. For example, the sensor can be attached to a grid, gaze, screen, finishing/covering element or rosette, for example. Also, one or more of the sensors can be provided in a room and/or building provided with the filter system according to the invention. This provides further information to the controller. The sensors may transmit and/or receive information to and/or from the controller with a wireless and/or wired protocol. This enables automatic control. The sensor may relate to a flow sensor configured for measuring quantity of air, a particle detector for detection of undesired particles, for example. It will be understood that the use of other sensor types can also be envisaged. In certain embodiments of the invention the filter system comprises a fan, and, optionally, the fan acts as a flow sensor providing information about the air flow to the controller.

The filter system according the invention prevents unnecessary energy usage that is caused by over-treating the indrawn air. Furthermore, this reduces the amount of ozone that is produced by the filter system. This provides an efficient and effective filter system.

Optionally, the combination of electrostatic and plasma filters does not require providing a conventional carbon filter. Omitting such conventional carbon filters from the filter system has the advantage that the maintenance requirements and cleaning efforts of such carbon filters are prevented. Furthermore, costs of the filter system are herewith reduced. Furthermore, this achieves a more constant performance of the filter system.

In presently preferred embodiments of the invention the outlet is provided with an insulating material, for example glass fibre material or any other suitable material. This insulating material preferably extends over the entire outlet in a direction substantially perpendicular to the (average) outgoing airflow through the outlet. This insulating material has sound reducing properties, thereby reducing the effects of the filter system of the invention on its surroundings.

In a presently preferred embodiment of the invention the inlet of the filter system is provided in an inlet housing.

By providing the inlet in an inlet housing the filter system is more flexible in relation to its dimensions. For example, the inlet housing is integrated in or with the filter housing. Alternatively, the inlet housing is provided separately from the filter housing and connected by a hinge or rotation axis, such that the inlet housing is movable relative to the filter housing. This enhances the flexibility of installing the filter system according to the invention. For example, when installing the filter system in an extractor hood of a kitchen, the available space is often limited. Providing the inlet in a separate inlet housing enables placing the filter system in a wide variety of extractor hoods and kitchen designs. As a further advantage, providing the inlet in a separate inlet housing provides the possibility to design the inlet and inlet housing, such that transfer of the noise produced by the filter system to its environment or surroundings is significantly reduced.

In a further preferred embodiment of the invention, the filter system comprises a motor configured to withdraw air from the environment or surroundings to provide the air to the suction opening of the filter system. In a presently preferred embodiment, the motor is placed in the inlet housing of the filter system. The motor may use a fan to withdraw air from the surroundings. Optionally, this fan acts as flow sensor and is operatively connected to the controller of the filter system. This provides an effective and efficient filter system.

In a further preferred embodiment of the invention, the filter housing is provided with an outlet surface extending over substantially the outer surface of the filter housing and having a width and height, wherein the height is smaller than the width. For example, the filter system has an inlet that is directed downwards and an outlet that is provided at the circumference of the filter housing, directing the airflow substantially horizontal. The filter housing extends in a vertical lengthwise direction. In the horizontal plane the filter housing has a height and a width. For circular housings, these heights and widths are substantially equal. In one of the preferred embodiments, the height is smaller than the width, thereby leading to an oval or rectangular shaped filter housing. This provides additional freedom to the design of the filter housing, thereby improving possibilities for installing the filter system in a wide variety of situations.

In an alternative embodiment of the invention, the filter housing further comprises a fan configured to generate energy for driving one or more of the filters of the filter system. In fact, the fan acts as a turbine and provides a stand-alone filter system. Such stand-alone filter system can be applied when the filter system is provided in a naturally or artificially generated airflow that drives the fan. Preferably, the fan acts as a sensor for the controller to activate and/or adjust settings of the filter system.

In a further preferred embodiment of the invention the controller comprises user inputs enabling separate activation of the electrostatic and plasma filters. This provides additional flexibility of the filter system of the invention with its characteristics being adaptive to the specific conditions wherein the filter system is being used.

In an advantageous embodiment according to the present invention, the controller further comprises a user interface.

By providing a user interface an effective operation of the climate system is achieved. The user interface can be wireless and/or wired. The user interface renders the climate system flexible and adjustable to the specific conditions in which it is used. Preferably, the user interface comprises a touch screen, a tablet, mobile phone or other electronic device. By providing the user interface as a touch screen, tablet, mobile phone or similar electronic device, a user has easy access to the operating parameters of the climate system. This enables the user to control and/or adjust the filtering operation in an effective manner. For example, a so-called app can be downloaded to enable control via the electronic device of a specific climate system. Furthermore, this enable remote access for installing a software update, maintenance and the like. Also, the system can optionally send a warning signal to the user thereby achieving an interactive system.

In a further advantageous preferred embodiment according to the present invention a conical body is provided in or close to the suction opening.

By providing a conical body, the air drawn in using the fan is guided as optimally as possible through the electric filter. The surface area of the whole filter is hereby also utilized as fully as possible.

The conical body preferably provided with a shape such that a substantially uniform air distribution through the filter is realized during use. This further increases the effectiveness of the system.

The conical body is preferably provided with a number of ribs for better guiding of the airflow thereby. It has been found here that it is advantageous to provide the ribs in a spiral shape so as to thereby further improve the guiding of the airflow.

In the system according to a preferred embodiment of the invention, air with contamination enters a pre-chamber along with the indrawn contaminated air. The conical body preferably guides the air to the filter parts. Formed in a second chamber are radical particles with which the cleaning reactions take place substantially in a third chamber between the electrodes, preferably at the position of a glass fibre (nano)mat, which holds the particles. Following the reactions, discharge preferably takes place via an active carbon mat with which excess ozone is also captured. The outer casing of the system is shaped such that a further sound reduction is thereby realized.

Preferably, the housing comprises a plastic housing. A safer system is realized by providing a plastic housing when compared to a metal housing due to the insulating character of the housing. In addition, the overall weight of the filter system according to the invention is also reduced. This makes it easier to handle the system and assemble it on site.

The invention further relates to an extractor hood comprising a filter system in one of the aforementioned embodiments.

Such extractor hood provides the same effects and advantages as stated for the filter system. Such extractor hood is typically included in a kitchen or kitchen facility.

The invention further also relates to a method for filtering air, the method comprising the steps of: - providing a filter system in an embodiment of the invention; - drawing in air through an inlet opening and through the carbon filter; - activating the plasma filter and provide ozone particles to the flow path after air passed through the carbon filter; and - filtering the indrawn air.

The method provides the same effects and advantages as those stated for the filter system and/or extractor hood.

Preferably, the method further comprises the step of providing user input with a user interface. This enables flexible operation of a climate system. The user interface preferably comprises a touch screen, tablet, mobile phone or other electronic device. This enables user friendly adjustments of controller settings.

It has been found that a self-cleaning action of the filters is realized with the preferred combination of filters as described above. This preferably realized self-cleaning action has a positive effect on the lifespan of the system and/or the time interval between maintenance operations.

Further advantages, features and details of the invention are elucidated on the basis of a preferred embodiment thereof, wherein reference is made to the accompanying drawings, in which: - figures 1A-E show a filter system according to the invention; - figures 2A and B show a filter system according to the invention with internal motor; - figures 3A-C show an alternative filter system of the invention according to the invention with integrated inlet housing; - figures 4A-C show a further alternative embodiment according to the invention with separate inlet housing; - figures 5A and B show a further alternative filter system according to the invention with a different shape of the outlet surface; - figures 6A and B show an alternative filter system according to the invention; - figure 7 shows a further alternative embodiment of the invention with extractor hood; and - figure 8 shows an alternative filter system operating as a turbine.

Filter system 1002 (Figures 1A-E) comprises housing 1004 with inlet 1006 end outlet 1008. Flow path 1010 starts from inlet 1004 towards outlet 1006 and continues from outlet 1006. Carbon filter 1012 is provided in flow path 1010 close to inlet 1004. In the illustrated embodiment plasma unit 1014 is provided as modular unit and can be connected to housing 1004 of system 1002. The generated ozone is added to the flow path after carbon filter 1012. Connector 1016 enables connecting system 1002 to the electrical grid, for example. Motor/fan 1018 is connected to inlet 1006 to draw in air. It will be understood that other configurations can also be envisaged in accordance to the present invention, optionally including an electrostatic filter and/or different configurations for motor/fan 1018. Sensor 1020 provided information about the air (amount, speed, and/or characteristics such as amount and/or type of pollution) to controller 1022. Optionally, controller 1022 is integrated in external controller 540. Sensor 1020 may include one or more of: pressure sensor, ozone sensor, C02 sensor. Carbon filter 1012 can be removed/changed by removing grid 1024. Optionally, (pressure controlled) non-return valve 1026 is provided that is optionally controlled by plasma unit 1014. Optionally, controller 1022, 540 measures flow resistance of carbon filter 1012 and indicate when cleaning or replacement of filter 1012 is required. Optionally, a timer is provided for such indication. In the illustrated embodiment, moisture regulating membrane 1028 is provided in front of carbon filter 1012.

It will also be understood that features of the embodiments shown can be exchanged and/or combined to further alternative embodiments in accordance to the invention. Also, additional functions can be performed by illustrated components. For example, plasma generator 1014 may add copper and/or silver ionen. Connector 1016 may involve a transformator/trafo.

Filter system 2 (Figures 2A-B) comprises a circumferential surface 4, bottom inlet 6, upper part or cover part 8. In the illustrated embodiment outlet surface 4 is provided with inclined openings 10. Airflow enters inlet 6 in direction A and leaves through outlet 4 in direction B. Fan 12 is driven by motor 14 that is activated and controlled by controller 16. Fan 12 directs air towards outlet surface 4. In the illustrated embodiment carbon filter 17 is provided in or near inlet 6. Electrostatic filter 18 comprises inner gaze, grid or screen 20 acting as first electrode and outer gaze, grid or screen 22 acting as second electrode. In the illustrated embodiment first electrode 20 is positively charged and second electrode 22 is negatively charged. First and second electrodes 20, 22 are provided at a distance relative to each other and a glass fibre filling material 24 is provided between electrodes 20, 22. On the other side of electrostatic filter 18 there is provided insulation filter 26 that is positioned directly against grid 28 of outer surface 4. Plasma generator 30 is provided in chamber 32 of filter system 2, or alternatively in the flow path after electrostatic filter 18. Optionally, electrostatic filter can be omitted from system 2. In the illustrated embodiment filter housing 34 comprises bottom plate 36, top plate cover 8, ring 38 and outer surface grid 28. It will be understood that other configurations can also be envisaged in accordance with the invention.

Second embodiment 102 (Figures 3A-C) illustrates a filter system with filter housing 104 and inlet housing 106 that are integrated into a single housing. In the illustrated embodiment, filter housing 104 and inlet housing 106 are rotatable around axis or shaft 108. A motor and/or fan 110 are provided in inlet housing 106. Supports 112 define inlet ports 114 that draw in air in direction A. Inside inlet housing 106 air is directed towards the inlet of filter housing 104 of filter system 102. Filter system 102 has a similar construction for optional electrode filter 116, optional carbon filter 117, and the optional plasma filter 118. Filter housing 104 is further provided with conical body 120, optionally provided with additional ribs. Air flow A is directed towards the outer surface in direction B with the use of conical body 120. In the illustrated embodiment outlet openings 122 extend in a horizontal direction relative to filter housing 104 and substantially parallel to top or cover plate 124. A third embodiment of filter system 202 (Figures 4A-C) is similar to filter system 102 with the exception that filter housing 204 and inlet housing 206 are provided separately. In the illustrated embodiment this requires external connecting cable 208. The operation of filter system 202 is similar to the illustrated second embodiment 102.

In a fourth embodiment filter system 302 (Figure 5) filter housing 304 has a rectangular or oval shape having width w and height h, wherein height h is smaller that width w. Furthermore, inlet housing 306 has an oval inlet opening and is provided with support 308. Inlet housing 306 can be slid into support 308. It will be understood that other embodiments are also possible. The oval or rectangular shape enables installing filter system 302 in relatively small spaces. A fifth embodiment filter system 402 (Figures 6A-B) is provided with filter housing 404 and inlet 406. Air flows in direction A and leaves direction B through outlet 408. Flow A is generated externally. Inside filter housing 404 there is provided fan 410 that starts rotating in the presence of flow A. therefore, fan 410 acts as an energy generating turbine capable of generating electricity to supply filters of filter system 402 that operate in a similar manner as described earlier for other embodiments. A sixth embodiment filter system 502 comprises a filter housing 504 with an inlet 506, conical body 508, outlet surface 510 (Figure 7). Conical body 508 is in the illustrated embodiment provided with ribs 512. It will be understood that ribs 512 can be omitted from conical body 508 and can also be provided with the other embodiments of filter system 2, 102, 202, 302, 402. Ozone generator 515 is connected to conical body 512.

Cone 508 is provided with printed circuit board 514 which is operatively connected to connector 516. Arranged on cone 508 is plasma generator 515 provided with ozone plate 518 which is arranged with a clamping part in or on generator 515. Printed circuit board 514 is provided with sensors 520 on the side directed downward during use. Outer casing 510 is provided with bracket 522 for mounting on for instance an extractor hood. The filter inlet is provided with grate 506. Cover 530 is provided with connector 532, buttons 534 and a connection 536 for plug/adapter 538 which is connected to connector 516.

Filter system 502 is connected to extractor hood 524 with extractor hood module 526 and air extraction module 528.

In a different embodiment of filter system 602 (Figure 8) ring shaped filter housing 604 is provided on pedestal 606 with arm 608. Filter system 602 acts as turbine with fan 610. In the illustrated embodiment the inside 612 of filter housing 604 is provided with ozone outlet 614 that are activated by fan 610. Filter system 602 can be used to filter outside air and/or outlet air of factories, for example.

Operation of filter systems 1002, 2, 102, 202, 302, 402, 502, 602 preferably involves the use of control panel 540 with display 542. When a filter system is activated, for example with control 540 in several of the embodiments a fan and/or motor will draw in air via the inlets. In some of the illustrated embodiments, sensors are arranged, optionally on the conical body, that will detect the presence, and type and/or level of contamination of the airflow. This signal is transmitted to the controller that can be cooperated into the encapsulated electronic space. The controller activates the ozone generator and/or electrostatic filter.

In the shown embodiment of system 1002, 2,102,202,302,402,502,602 the voltage used preferably lies in the range of 0.05 Volt-10 kV, more preferably in the range of 0.5-2 kV in normal ambient conditions. A voltage of 2-4 kV is employed for the optionally provided ozone generator.

In the shown embodiment a standby mode is provided which can if desired be continuously “active”.

It will be apparent that combinations with other types of filter are also possible. Filter system 2 can also be utilized in applications other than in extractor hood or building. For example, the filter system can be applied to kitchen facility, more specifically an extractor hood, an exhaust pipe, in the outside air etc. Alternatively, the filter system is provided in open room such as in a vehicle, airplane, building, etc.

Assembly of the filter system begins with a grating or mesh or grid, following which a second grating or mesh is provided at a short distance, for instance 40 mm, such that an inner and an outer annular cross-section are provided. This is the core of electrostatic filter 18, for example. The grids are connected. A glass fibre mat is preferably arranged in the intermediate space. Isolation mat 26 is arranged on the outer side. An ozone element 30 is subsequently arranged in a housing which is then optionally placed on conical element 508, for example. The conical element can then be placed in the interior, where after the wiring can be connected. An end plate can be arranged following placing. In a currently preferred embodiment a printed circuit board is then adhered fixedly in the filter housing. The end plate with sensor can subsequently be arranged so that filter system is mounted and can be applied. A filter system has been tested in an experiment in a kitchen. Recirculation was started at about 200 m3/hour for about 10 minutes prior to the cooking process in order to bring about a good circulation. In the applied situation the ozone binds the undesired particles with an efficiency of about 95%. The noise reduction realized was about 25% compared to the conventional extraction.

It will be understood that different features and embodiments of the illustrated filter systems can be exchanged and/or combined resulting in additional alternative embodiments according to the invention. For example, the conical body can be applied to different embodiments or be omitted therefrom. The conical body can be provided with ribs or grooves optionally. The turbine operation or a fan can be provided in different embodiments of the filter system. Also, different types of sensors can be applied and combined in the different embodiments. Also, other features can be applied to the different embodiments.

The present invention is by no means limited to the above described preferred embodiments thereof. The rights sought are defined by the following clauses, within the scope of which many modifications can be envisaged. The filter according to the invention complies with the required standards, including the Dutch NEN 7120. The filter is quickly mountable, also when applied in existing and conventional extractor hoods. In a currently preferred embodiment settings are preferably provided in adjustable and re-adjustable manner, preferably on a printed circuit board of the filter.

Claims (20)

A flow filtering system comprising: a filter housing with an inlet opening for inlet of an incoming flow and an outlet for outlet of a filtered flow, the filter housing defining a flow path for the incoming air; a carbon filter provided in the flow path and configured to filter the incoming air; and a plasma filter provided in the flow path downstream of the carbon filter and configured to generate ozone and provide the ozone to the incoming flow. The filter system of claim 1, further comprising: a sensor configured to measure the characteristics of the incoming air flow and capable of generating measurement input; and a controller operatively connected to the sensor, the controller comprising an ozone activator configured to activate the plasma filter in response to the measurement input. A filter system according to claim 1 or 2, wherein the sensor comprising a flow sensor configured to measure the incoming air flow. A filter system according to claim 1, 2 or 3, wherein the sensor comprising a particle detector configured to detect unwanted particles. The filter system of any preceding claim, further comprising: an electrostatic filter configured to electrostatically filter the incoming flow, the electrostatic filter comprising a first mesh as a first electrode and a second gas spaced therefrom as a second electrode , and a filler material provided between the first mesh and the second mesh. A filter system according to any of the preceding claims, wherein the plasma filter is releasably connected to the filter housing. A filter system according to any one of the preceding claims, wherein the inlet is provided in an inlet housing. The filter system of claim 7, wherein the inlet housing is movable relative to the filter housing. A filter system according to any one of the preceding claims, further comprising a motor configured for admitting air from the environment of the filter system and providing the air at the inlet port of the filter system. A filter system according to any one of the preceding claims, wherein the filter housing is provided with an outlet surface extending substantially over the outer surface of the filter housing and provided with a width and a height, the height being smaller than the width. A filter system according to any one of the preceding claims, wherein the filter housing further comprising a fan configured to generate energy for driving one or more of the filters of the filter system. The filter system of claim 11, wherein the fan acts as a sensor for the controller. A filter system according to any one of the preceding claims, wherein the outlet is provided with a non-carbon filter. A filter system according to any one of the preceding claims, wherein the controller comprises user input for enabling activation of the electrostatic and plasma filters. The filter system according to any of the preceding claims, wherein the controller further comprises a user interface. The filter system of claim 15, wherein the user interface comprises a touchscreen, tablet, or mobile phone. A filter system according to any one of the preceding claims, wherein a conical body is provided in or near the suction opening such that in use a substantially uniform air distribution is obtained through the filter. 18. Extractor hood comprising a filter system according to one of the preceding claims. A method for filtering air, comprising: providing a filter system according to any of the preceding claims 1-17; sucking in air through a suction opening and through the carbon filter; activating the plasma filter and supplying ozone particles to the flow path after the air has passed the carbon filter; and filtering the aspirated air. The method of claim 19, wherein the filter system has a self-cleaning effect during use.