WO2009106804A2

WO2009106804A2 - A grease filter and a ventilation arrangement incorporating such a filter

Info

Publication number: WO2009106804A2
Application number: PCT/GB2009/000498
Authority: WO
Inventors: Michael Leon Shaw
Original assignee: Michael Leon Shaw
Priority date: 2008-02-26
Filing date: 2009-02-25
Publication date: 2009-09-03
Also published as: GB2470142B; WO2009106804A3; GB201013756D0; GB0803458D0; GB2470142A

Abstract

A grease filter (1, 31) comprises a first frame (2) in which is mounted a first set of baffles (4) and a second frame (3) in which is mounted a second set of baffles (5). The second frame (3) is disposed adjacent the first frame (2) such that the first and second sets of baffles (4, 5) interleave to define therebetween one or more air pathways (10) through the filter (1). A connecting means (11) connects the first and second frames (2, 3) together and is releasable to permit the frames (2, 3) and therefore the two sets of baffles (4, 5) to move apart, in particular to permit the filter (1) to be thoroughly cleaned. Preferably, the frames (2, 3) slide relative to one another between a first position wherein the air pathway or pathways (10) are open and a second position wherein the air pathway or pathways (10) are closed. The grease filter (1, 31) therefore also acts as a fire damper and a ventilation arrangement (20) incorporating such a filter (1) need not also incorporate a fire damper.

Description

A GREASE FILTER AND A VENTILATION ARRANGEMENT INCORPORATING SUCH A FILTER

The present invention relates to a grease filter for use primarily, but not exclusively, in a ventilation hood of a kitchen ventilation system and to a ventilation arrangement incorporating such a filter.

In a kitchen it is usual for a ventilation hood linked to ventilation ducting to be installed above a cooking appliance in order to extract the hot air, steam and fumes generated by use of the appliance from the kitchen. These fumes typically comprise grease droplets, small-scale particulate materials, undesirable odours, including heavy cooking vapours, and, .from time to time, smoke.

A grease filter is a typical component of a ventilation hood as otherwise grease-laden fumes from cooking will rapidly deposit a heavy layer of grease in the hood, on the air extraction means used in the ventilation system and in any associated ducting. This would create a fire hazard as well as being unhygienic and a source of objectionable odours. The grease filter may be, therefore, the first filter of several that may be encountered by air being drawn through a ventilation system. A grease filter typically comprises a mesh or a series of baffles and is designed to operate by forcing air drawn through it to change its direction of travel abruptly prior to exiting the filter. As the air changes direction, grease and other impurities are propelled away from the air stream and impinge upon the mesh or baffles where they either stick or run into a collection area. To operate effectively and efficiently, the air must be drawn through the grease filter at a predetermined speed and conventional ventilation systems are designed to extract air through the grease filter at the required rate to ensure that it operates effectively and efficiently.

However, the problem with such grease filters is that they are difficult to clean. The labyrinthine path along which grease -laden air travels through the filter makes them particularly difficult to clean effectively as many of the surfaces to which the grease sticks are hidden within the body of the filter and cannot be accessed directly for cleaning.

The object of the present invention is to provide a grease filter for a kitchen ventilation system that overcomes or substantially mitigates the aforesaid disadvantage.

According to a first aspect of the present invention there is provided a grease filter comprising a first frame in which is mounted a first set of baffles; a second frame in which is mounted a second set of baffles, the second frame being disposed adjacent the first frame such that the first and second sets of baffles interleave to define therebetween one or more air pathways through the filter; and a connecting means that connects the first and second frames together that is releasable to permit the frames and therefore the two sets of baffles to move apart.

Preferably, the connecting means comprises one or more pins that are each connected to one of the frames and pass through an aperture in the other of the frames to hold the frames together.

Preferably also, each set of baffles comprises a series of side-by side channel-shaped members, the base of each of the channel-shaped members being arranged to lie on one or other of exterior faces of the filter and the sides of each of the channel-shaped members in one set of baffles interleaving with the sides of the channel-shaped members in the other set of baffles.

Preferably also, the frames slide relative to one another between a first position wherein the air pathway or pathways are open and a second position wherein the air pathway or pathways are closed. Grease filters are not normally capable of being opened or closed. However, by providing for this possibility the present invention enables the filter to be used in a ventilation system and to fulfil the dual role of a grease filter and a fire damper. In ventilation systems that incorporate a fire damper, the fire damper is adapted to be closed on detection of a fire or of smoke to prevent air from outside the building being drawn through the ventilation ductwork to feed the fire and to prevent fire from spreading via the ventilation system into the rest of the building structure. By using embodiments of the present invention that can be controllably opened or closed, it is not necessary to include in a ventilation system an additional fire damping means. This makes such a system more cost effective and efficient than many conventional arrangements.

Hence, according to a second aspect of the present invention there is provided a ventilation arrangement comprising a grease filter according to the first aspect of the present invention.

Preferably, the grease filter comprises frames that slide relative to one another between a first position wherein the air pathway or pathways are open and a second position wherein the air pathway or pathways are closed.

Preferably also, the ventilation arrangement also comprises an actuator adapted to control the movement of one frame relative to the other to thereby control opening and closing of the or each air pathway through the filter.

Further preferred but non-essential features of the various aspects of the present invention are further described in the dependent claims appended hereto.

The various aspects of the present invention will now be described by way of example with reference to the accompanying drawings, in which:- - A -

Fig. l is an front elevation of a grease filter according to the first aspect of the present invention;

Fig. 2 is a transverse cross section along the line II-II in Fig. i showing first and second frames of the filter in a first relative position wherein the air pathways through the filter are open;

Fig. 3 is a view similar to Fig. 2 but showing the first and second frames of the filter in a second relative position wherein the air pathways through the filter are closed;

Fig. 4 is a view similar to Figs. 2 and 3 but showing first and second frames of the filter separated;

Fig. 5 is an end elevation of the filter in the direction of arrow V in Fig. 1;

Fig. 6 is a front elevation of a filter assembly incorporating three grease filters as shown in Figs. 1 to 5;

Fig. 7 is an end elevation of the assembly shown in Fig. 6; and

Figs. 8 and 9 are views similar to Figs 2 and 3 respectively but showing a filter with baffles having a slightly different shape.

As shown in Figs. 1 to 5, an embodiment of grease filter 1 according to the first aspect of the invention comprises first and second frames 2 and 3 in which are mounted first and second sets of baffles 4 and 5 respectively (see Fig. 4, in particular). The frames 2 and 3 are rectangular and the second frame 3 is smaller than and disposed within the first frame 2 such that it can slide from side to side relative thereto, as is described in further detail below. In use, the frame 2 forms part of a front face of the filter 1 and the frame 3 forms part of a rear face of the filter 1.

Each set of baffles 4, 5 comprises a series of side-by-side channel- shaped members 6. The base 7 of each of the channel-shaped members 6 is arranged to lie on one or other of the two exterior faces of the filter 1 and the sides 8 of each of the channel-shaped members 6 in one set of baffles 4, 5 inter-leaves with the sides 8 of the channel-shaped members 6 in the other set of baffles 5, 4. In the illustrated embodiment, the channel-shaped members 6 in each set of baffles are arranged in pairs to define an 'm' or 'w' shape, as shown in particular in Fig. 4. The inner sides 9 of the each pair of channel-shaped members is, therefore, conjoined or shared. It will be appreciated, however, that in other embodiments, the channel-shaped members 6 could be left singly or conjoined in other ways.

In a first relative position of the frames 2, 3 the interleaving sides 8 of the two sets of baffles 4, 5 are spaced apart, as shown in Fig. 2, such that they define a plurality of air pathways, shown in dashed lines 10, through the filter 1 from the front face to the rear face. Each of these pathways 10 is substantially S-shaped so that the air travelling along it is forced to change its direction of travel abruptly prior to exiting the filter 1. As the air changes direction, grease and other impurities are propelled away from the air stream and impinge upon the baffles 4, 5 where they either stick or run along the baffle into a collection area, as described below. However, in a second relative position of the frames 2, 3 as shown in Fig. 3, the sides 8 of the two sets of baffles 4, 5 lie in contact with one another so that the air pathways 10 are closed off and airflow through the filter 1 is prevented.

The two frames 2 and 3 are connected together by a connecting means which is releasable so that the two frames 2 and 3 can be separated, as shown in Fig. 4. This means that the filter 1 can be demounted and opened up to permit efficient cleaning. The connecting means also enables the frames 2 and 3 to move relative to one another between the first and second position described above to permit the filter to move from an open to a closed position and vice versa.

In the illustrated embodiment, the connecting means comprises four pins, which are located in pairs ii, 12 on opposite sides of the filter 1, each pin being adjacent one of the comers of the filter 1. The pins are each connected to one of the frames 2, 3 and pass through an aperture in the other of the frames 3, 2 to hold the frames together. In particular, on one side of the filter 1, the pins 11 comprise a stud with an exterior screw-threaded portion 13 adjacent a head 14 that is screwed into a tapped nut 15 connected to the outer frame 2. The projecting end of each pin 11 slides through a bush 16 connected to and aligned with an aperture through the inner frame 3. The pins 11 are therefore removable as they can be unscrewed from the nut 15 and withdrawn from the bush 16. In contrast, on the opposite side of the filter 1, the two pins 12 each comprise a stud that is secured to the outer frame 2 and slides through a bush 17 connected to and aligned with an aperture through the inner frame 3. A spring 18 is located around that part of the pin 12 located between the two frames 2, 3 such that the force of the spring 18 forces the frames 2, 3 to adopt their first position wherein the air pathways 10 are open. The pins 12 are permanently fixed to the outer frame 2 so that to move the two sets of baffles 4, 5 apart, the pins 11 must be detached from the outer frame 2 and withdrawn to enable the inner frame 3 to be pulled off the pins 12. The inner frame 3 is then separate from the outer frame 2, as shown in Fig. 4. When it is desired to reconnect the two frames 2, 3, then the inner frame 3 should be relocated on the pins 12 by passing the pins 12 through bushes 17. The pins 11 can then be passed through the nuts 15 and inserted into the bushes 16 before being screwing the screw-threaded portion 13 back into the nuts 15.

Whilst the illustrated embodiment of filter 1 described above comprises two frames 2 and 3 that separate so that they can be cleaned, it will be appreciated that different forms of connecting means could be employed such that the two frames 2 and 3 are hinged together and can open out for cleaning. Different forms of releasable connecting means may also be used, such as clips or push-fit arrangements.

The filter i is intended to be mounted in a filter assembly 20, as shown in Figs. 6 and 7. Such a filter assembly is then itself mounted in a ventilation hood of a ventilation arrangement. The illustrated assembly 20 comprises a bank of three filters 1, each of which is provided with an adjacent lamp 21 to illuminate the work area beneath the ventilation hood and an actuator motor 22 which controls opening and closing of the filter 1. The lamps 21 are mounted in the front face of the casing 23 of the assembly 20 but the motors 22 are hidden within the casing 23 behind access doors 24. The interior of the casing 23 is connected to conventional ventilation ductwork that will not be further described. To enable each of three filters 1 to be detached from the casing 23 prior to being opened for cleaning, the outer frame 2 of each filter 1 is provided with a pair of handles 25, one at each side, that project from its front face. The handles 25 enable the filter 1 to be manoeuvred out through an opening in the casing 23 in which it is located from a seat in which the filter 1 is normally retained.

Each filter 1 is mounted in the assembly 20 such that the channel- shaped members 6 of the baffles 4, 5 of the filter 1 run from the top to the bottom of the assembly 20. In this way, any grease or other impurities that do not stick to the baffles 4, 5, run down them to the lower side of the filter 1 where they collect and drip out of weep holes 26 formed in the outer frame 2. This liquid material then drips to the bottom of the casing 23 where it is collected in a tray 27 located at the base of the assembly 20. The tray 27 can itself be periodically demounted for cleaning along with the filters 1.

Each filter 1 within the assembly 20 is operable independently of the other two. In particular, in order to close the filter 1, the frame 3 is moveable from its first position into its second position by sliding the inner frame 3 relative to the outer frame 2 against the force of the springs 17. Within the assembly 20 this is accomplished by an arm 28 that is attached to the motor 22 associated with the frame l. The arm 28 passes through an aperture 29 formed in one side of the outer frame 2 and bears directly against the frame 3 on the opposite side thereof to the pins 12. Operation of the motor 22 causes the arm to be rotated so that it moves through the aperture 29 and pushes against the frame 3 to move it into its second position relative to the frame 2. Deactivation of the motor 22, enables the springs 17 to move the frame 3 relative to the frame 2 in the opposite direction to open the filter 1 and to push the arm 28 back to its initial position outside the filter 1. Operation of the motor 22 is initiated by a control means (not shown) linked to one or more sensors. In the illustrated embodiment (see Fig. 6), each filter 1 is provided with a heat sensor and a smoke detector that are respectively located behind the two ports 30 in the front face of the casing 23 of each filter 1 on either side of the lamp 21. An external carbon monoxide sensor may also be provided as part of the ventilation system and linked to the control means for the motor 22.

Whereas as in the filter 1 shown in Figs. 2 and 3, the sides 8 of the channel-shaped members are planar, in a modified filter 31, as shown in Figs. 8 and 9, the outer sides 8 of the channel-shaped members 6 in each set of baffles have an angled portion 32 formed along their free end. The portions 32 of the members 6 in each frame 2, 3 are angled so as to be parallel and point in the same direction as one another. This means that in the second relative position of the frames 2, 3 as shown in Fig. 9, the blade- like edges of the portions 32 of one frame make contact with the sides 8, 9 of the members 6 of the other frame to close the filter 31. Hence, rather than the sides 8, 9 of the members 6 having to make contact with one another by lying contiguously, as shown in Fig. 3, it is sufficient in this modification for the edges of each of the portions 32 to make contact with the side 8, 9 of its adjacent member 6. This improves the air-tightness of the closure as slight differences in the parallel alignment of the sides 8 and 9 of the members 6, which can easily occur when the filter is being cleaned, will not prevent the filter 31 from closing adequately. In both the embodiment of grease filter i described above and the modified filter 31, the frame 3 is moveable from its first position into its second position by sliding the inner frame 3 relative to the outer frame 2 against the force of the springs 17, in a side to side movement. It should be appreciated, however, that both filters 1, 31 could also be closed by transverse movement of one of the frames 2, 3 relative to the other so that the edges of the sides 8 of each of the channel-shaped members 6 in one set of baffles 4, 5 contacts the base 7 of the channel-shaped members 6 in the other set of baffles 5, 4. This would again close off the air pathways 10 through the filter 1. In the first embodiment, closure of the air pathways 10 would occur when the frames 2 and 3 moved towards one another. However, in the modified arrangement, partial closure would also take place if the frames 2 and 3 are moved away from each other as the angled portions 32 of the channel-shaped members 6 in each frame will contact one another and close off the air pathways 10. Complete closure could be arranged if the inner sides 9 were also to be provided with an angled portion.

In such a filter a spring loading would be arranged to act in a normal direction to that of the embodiment described above against the force of a motor arm that acted to push one of the frames 2, 3 transversely closer to the other frame 3, 2. In other embodiments of filter, the channel section baffles 6 of at least one of the frames 2, 3 could be adapted to rotate or swivel from a position wherein the sides 8 thereof close the filter into an open position wherein the sides 8 of the baffle members interleave to define a plurality of air pathways through the filter.

In use, the filters 1, 31 are maintained in an open position and operate in a conventional fashion as grease filters. From time to time they should be demounted from the assembly 20, opened up and cleaned thoroughly before being replaced back in the assembly 20. However, if the heat sensors detect a temperature at or above a predetermined threshold, which should be a temperature indicative of a fire or potential fire hazard in the work area beneath the assembly 20, then the sensors activate the relevant motor 22 so that the associated filter l is closed. This prevents the ventilation system from sucking air through the filter i that may feed the fire below. As soon as the temperature falls below the threshold temperature, the sensors deactivate the relevant motor 22 to allow the filter 1 to open and the ventilation system to operate to clear any fumes and smoke. In this situation, therefore, the grease filters 1 act as fire dampers and then as smoke vents. In a similar way, provided that a temperature at or above a predetermined threshold heat is not detected by the heat sensor but either smoke is detected by the smoke detectors or the presence of carbon monoxide within the kitchen is detected by the carbon monoxide sensor, then the motors 22 of the filters 1, 31 are operated to open any closed filter 1 so that the ventilation system can operate to clear the smoke and fumes. Once the sensors indicate that the kitchen environment is back to normal, then operation of the filter 1 as a simple grease filter can be resumed.

It will be appreciated, therefore, that the ventilation arrangement operates more efficiently than many conventional systems because the closable grease filter 1, 31 obviates the requirement for a separate fire damper and/or smoke vent. A filter assembly 20 incorporating one or more filters 1 also has the additional advantage that it can be retro-fitted into most existing kitchen ventilation systems by replacing an existing assembly 20 with one as described above.

Claims

1. A grease filter comprising a first frame in which is mounted a first set of baffles; a second frame in which is mounted a second set of baffles, the second frame being disposed adjacent the first frame such that the first and second sets of baffles interleave to define therebetween one or more air pathways through the filter; and a connecting means that connects the first and second frames together that is releasable to permit the frames and therefore the two sets of baffles to move apart.

2. A filter as claimed in Claim l, wherein the connecting means comprises one or more pins that are each connected to one of the frames and pass through an aperture in the other of the frames to hold the frames together.

3. A filter as claimed in Claim 1 or Claim 2, wherein at least one of the connecting means comprises a stud with an exterior screw-thread that is screwed into a tapped nut connected to one of the frames and that slides through a bush connected to the other of the frames.

4. A filter as claimed in any of Claims 1 to 3, wherein at least one of the connecting means comprises a stud that is secured to one of the frames and that slides through a bush connected to the other of the frames.

5. A filter as claimed in any of Claims 1 to 4, wherein each set of baffles comprises a series of side-by side channel-shaped members, the base of each of the channel-shaped members being arranged to lie on one or other of exterior faces of the filter and the sides of each of the channel-shaped members in one set of baffles inter-leaving with the sides of the channel-shaped members in the other set of baffles.

6. A filter as claimed in Claim 5, wherein the channel-shaped members are arranged in pairs to define 'm' or 'w' shaped baffles, the inner sides of the each pair of channel-shaped members being conjoined or shared.

7. A filter as claimed in Claim 5 or Claim 6, wherein sides of the channel- shaped members have an angled portion along their free ends.

8. A filter as claimed in Claim 7 when dependent on Claim 6, wherein the outer sides of each pair of 'm' or W shaped baffles have said angled portions.

9. A filter as claimed in Claim 7 or Claim 8, wherein the angled portions of the channel-shaped members in each frame are angled so as to be parallel and point in the same direction as one another.

10. A filter as claimed in any of Claims 1 to 9, wherein the frames slide relative to one another between a first position wherein the air pathway or pathways are open and a second position wherein the air pathway or pathways are closed.

11. A filter as claimed in Claim 10, wherein the connecting means is spring-loaded such that relative sliding movement of the frames into their second position is countered by the force of the spring-loading.

12. A filter as claimed in any of Claims 1 to 11, wherein the frames are rectangular and the second frame is disposed within the first frame.

13. A filter as claimed in Claim 12, wherein the connecting means are located on opposite sides of the filter adjacent the corners of the frames.

14- A filter as claimed in Claim 13 when dependent on Claims 3 and 4, wherein on one side of the filter the connecting means comprises the aforesaid stud with an exterior screw-thread that is screwed into a tapped nut connected to one of the frames and that slides through a bush connected to the other of the frames, and on the opposite side of the filter the connecting means comprises the aforesaid stud that is secured to one of the frames and that slides through a bush connected to the other of the frames, a spring being located around the latter stud between the two frames.

15. A ventilation arrangement comprising a grease filter as claimed in any of Claims 1 to 14.

16. An arrangement as claimed in Claim 15 comprising a grease filter as claimed in Claim 10 and an actuator adapted to control the movement of one frame relative to the other to thereby control opening and closing of the or each air pathway through the filter.

17. An arrangement as claimed in Claim 16, wherein the actuator comprises a motor that actuates an arm which pushes one of the frames to cause it to slide relative to the other frame against the force of a spring return means.

18. An arrangement as claimed in Claim 16 or Claim 17, wherein the ventilation arrangement comprises a heat sensing means linked to the actuator whereby on detection of a temperature at or greater than a predetermined threshold by the sensing means, the actuator operates to close each or each air pathway through the filter.

19. An arrangement as claimed in Claim 18, wherein the ventilation arrangement comprises a smoke detector linked to the actuator whereby on detection of smoke, the actuator operates to open each or each air pathway through the filter provided that the sensing means does not detect a temperature at or greater than the predetermined threshold.

20. An arrangement as claimed in Claim 18 or Claim 19, wherein the ventilation arrangement comprises a carbon monoxide sensor linked to the actuator whereby on detection of carbon monoxide, the actuator operates to open each or each air pathway through the filter provided that the sensing means does not detect a temperature at or greater than the predetermined threshold.