GB2133835A - Kitchen exhaust fans - Google Patents

Abstract

The fan 4 is located within a cylindrical housing 2 having an air inlet 21, a generally tangential extension 23 with a sloping base 25 and an air outlet 22. Three or more apertures for draining liquid are located in the base of the housing. A tray 5 directs liquid or oleaginous material contained in the gases generated during cooking, from the various drain apertures via a tube 51 into a container 6. The fan is cleaned by spraying aerosol detergent into it and draining the detergent into the container 6. <IMAGE>

Description

SPECIFICATION Kitchen exhaust apparatus The present invention relates to kitchen exhaust fans, and particularly to an apparatus capable of separating liquid components, such as oleaginous substances, from the heated vapor and smoke released during a cooking process, so as to discharge the liquid components and gases through separate outlets.

Prior art exhaust fans generally include a motor-driven fan mounted in a casing having an inlet port and an outlet port for exhausting gaseous emissions generated during a cooking process in the kitchen. A problem incident to such exhaust fans is that in cooking food products of greasy nature, especially Chinese cuisine, oleaginous components entrained in the vapor or smoke tend to be separated from same by the centrifugal force produced by the rotating fan, so as to deposit on the fan, the interior surfaces of the casing, and the surrounding area of the inlet port. These oleaginous components accumulate in droplets, which may sometimes be spattered out from the rim of the inlet port and drop down on the food being cooked thereby to contaminate the food.Particularly, the oleaginous substances may also condense in large quantities to become gelatinous masses plugging the gap between the inlet port and the fan blades. Periodical cleaning of the exhaust fan to remove these gelatinous masses is difficult and time-consuming.

Various means for overcoming the abovementioned disadvantages have been suggested.

For example, the inlet port of the casing may be covered with a filter screen so that larger oleaginous components are absorbed by the filter screen when gaseous emissions containing them are drawn into the casing. There may also be provided an annular groove around the inlet port, or a hole in the lowest rear portion of the casing, so that centrifugally separated oleaginous components may be collected in the annular groove or converged to the hole to be removed manually. However, the above-mentioned devices may not achieve their desired effect. For instance, while the filter screen is effective in entrapping oleaginous components, it then becomes an obstacle to gas flow through the inlet port, and thus lowering the efficiency of the exhaust fan.

Consequently, for efficiency as high as those fans without a filter screen, a motor of higher power is required and hence more electrical energy is consumed. Even then, since the oleaginous components adhering to the filter screen reduce the total pore area of the filter screen, the filter screen must still from time to time be removed from the inlet port to be cleaned, otherwise, the accumulated oleaginous components may be melted by the heat generated during cooking and drop down on the food being cooked, thereby contaminating it.

The invention sets out to provide apparatus which can overcome the above-mentioned disadvantages, and which can effectively separate oleaginous and liquid components from gaseous emissions generated during a cooking process and prevent the oleaginous and liquid components subjected to centrifugal force from being thrown out of the inlet port of the fan housing by directing and collecting such components, so as to ensure that the food being cooked and the kitchenware will not be contaminated.

The kitchen exhaust apparatus described below permits easy, quick and automatic cleaning of the fan blades and the interior of the fan housing by spraying through the inlet port a detergent into the apparatus while in use.

In one aspect the invention provides a kitchen exhaust apparatus including a volute housing in which is mounted a motor-driven centrifugal fan, said volute housing having (a) a generally cylindrical portion surrounding the fan blades and having a base with an inlet port and (b) a generally tangential extension thereto formed with an upwardly-inclined sloping base and a gas outlet port above the slope, in which at least one first drain aperture is provided at or near the base of the slope, and at least one second drain aperture is disposed in the base of the cylindrical portion, generally at the starting point of the said base nearest the tangential extension in the sense of fan movement, a gathering plate being attached to the underside of the volute housing for joint collection of oleaginous and liquid components dropping down from said first and second drain apertures.

The invention will be further described with reference to the accompanying drawings, wherein: Figure 1 is a longitudinal section of apparatus according to the invention; Figure 2 is a cross-section taken on line I-I of Fig. 1 , showing the apparatus after a motor and fan have been disassembled therefrom; Figure 3 is an exploded view in perspective of a housing and gathering plate detached from the apparatus according to the invention; and Figures 4 and 5 are cross-sections of the housing of the apparatus, illustrating drain apertures arranged in different forms.

In the apparatus of Figs. 1 to 3, a main housing 1 is inclined rearwardly at an angle of 3c1 50 so that any fluid which may be left in the apparatus will automatically flow to the lower rear part. A volute fan housing 2, mounted in the main housing 1, houses a centrifugal fan 4 adapted to be operated by an electrical motor 3 fixed to the main housing 1 above the centrifugal fan 4. The impeller of the centrifugal fan 4 is located above an inlet port 21 formed in the base 24 of the volute housing 2. An outlet port 22 is provided above the extended end portion 23 of the volute housing 2 and protrudes upwardly through the main housing 1.

A gathering plate 5, best shown in Fig. 3, is fastened to the underside of the base 24 of the volute housing 2 adjacent to the extended end portion 23 of the housing 2. The gathering plate 5 is a generally L-shaped shallow plate with a drain tube 51 depending from the underside of the rear end of the gathering plate. In Fig. 1 a container 6 is shown detachably attached to the lower end of the drain tube 51 of the gathering plate 5.

The extended end portion 23 of the volute housing 2 has a gradually upwardly inclined slope 25. The base 24 of the volute housing 2 is provided with drain apertures 26, 27, 28 for drawing off any liquid which may be left in the volute housing. The drain aperture 26 lies adjacent the point where the extended end portion 23 is tangent to the cylindrical portion 20 of the volute housing. The drain aperture 28 lies near the corner where a side wall 29 (Fig. 2) of the tangential extension 23 meets the slope 25 of the volute housing.The drain aperture 27, which is preferably shaped as a narrow slot as shown in Fig. 3, lies adjacent the intersection of the peripheral wall of the cylindrical portion 20 and that side wall of the tangential extension 23 which is opposite to the side wall 29 i.e. generally at that "starting point" of the base of the cylindrical portion nearest the tangential extension when considered in the sense of fan movement. The drain apertures 26, 27 and 28 all communicate with the gathering plate 5 attached to the underside of the volute housing 2.

As shown in Fig. 3, the gathering plate 5 is fastened to the volute housing 2 by screws 52 located between the slope 25 and the inlet port 21. The gathering plate 5 has an outlet 53 leading to the drain tube 51 and is divided into compartments 54 by spacing members 55, for guiding any liquid in the plate into the outlet 53.

Of course, any liquid in the plate would tend to flow to the outlet 53 even without the spacing members 55, because of the inclination of the main housing 1.

Figs. 4 and 5 show alternative arrangements of drain apertures in the base 24 of the volute housing. Whereas the drain aperture 28 (adjacent the slope 25) as shown in Figs.1,2 and 3 is a round hole, in the embodiment of Fig. 4, it is replaced by a plurality of spaced-apart aligned drain slots 28. In the embodiment of Fig. 5, the said round hole 28 is still present but supplemented by a plurality of parallel angled drain slots 28a. In both Figs. 4 and 5, the drain aperture 27 is provided as previously described and the drain aperture 26 is absent; however drain aperture 26 may still be provided as will be explained beiow.

The mode of operation of the apparatus is as follows.

When the motor 3 causes the fan 4 to rotate, gaseous emissions containing oleaginous and liquid components are drawn through the inlet port 21 into the volute housing 2. Centrifugal force created by the rotary motion of the radial blades of the fan 4 acts to throw the gaseous emissions around the inner peripheral wall of the volute housing. The oleaginous and liquid components of greater specific gravity than the gases in the gaseous emissions, are centrifuged out of the gas flow. A proportion of the oleaginous components is thrown directly to the drain aperture 26 in the direction indicated by the arrows shown in Fig. 2. When the remainder of the oleaginous components, and the gas, hits the slope 25, the gas discharges through the outlet port 22 and the oleaginous components condense in droplets and slide down the slope 25 towards the inlet port 21.The oleaginous components will therefore trickle through the drain aperture 27, drop down on the gathering plate 5, and eventually flow into the container 6 via outlet 53 and drain tube 51.

According to the experiments conducted by the inventor with the same exhaust apparatus under the same condition, the effectiveness of the apparatus varies in accordance with variations in the number and arrangement of drain apertures provided, as follows: (1) Where only the drain aperture 26 is provided: If 20 c.c. of aerosol fluid is sprayed through the inlet port 21 into the housing 2 when the apparatus is in use, a splash of the fluid out from the rim of the inlet port is immediately observed. If 300 c.c. of the aerosol fluid is sprayed into the housing instead of the 20 c.c. then the splash of fluid from the inlet port is extremely serious and no fluid is found dropping down through the drain aperture 26.

(2) Where only the drain aperture 28 is provided: If 1 50 c.c. of aerosol fluid is sprayed into the housing when the apparatus is in use, a small proportion of the fluid will splash out from the rim of the inlet port but a large proportion of the fluid drains through the aperture 28.

(3) Where only the drain aperture 27 is provided: If 200 c.c. of aerosol fluid is sprayed into the apparatus in use, only a small amount of the fluid will splash out. However, if less than 200 c.c. of the aerosol fluid is sprayed into the apparatus, then there will scarcely be any splash of the fluid and a large amount of the fluid will drain through the aperture 27. The drain takes a longer time than the draining described in the preceding paragraph (3). A small amount of the fluid will collect in the gathering plate at a position corresponding to the aperture 28.

(4) Where both drain apertures 27 and 28 are provided: If 200 c.c. of aerosol fluid is sprayed into the apparatus, virtually no splash of the fluid is seen and a large proportion of the fluid drains through the apertures 27 and 28.

Thus, oleaginous and liquid components contained in gaseous emissions generated during cooking can be effectively separated and gathered for discharge by the apparatus of the invention.

There will be no splashing of oleaginous components from the rim of the inlet port which would otherwise contaminate the food being cooked, or the kitchenware. In particular, contamination of the interior surfaces of the apparatus and the fan by oleaginous components adhering thereto over long periods of use can be easily and quickly cleaned by spraying an aerosol detergent into the apparatus through the inlet port, since the detergent will be thrown around against the fan blades and the inner side wall of the housing and flow into the container 6 through the drain apertures and outlet 53. Accordingly, cleaning of the apparatus can be conveniently accomplished by spraying an aerosol detergent into the apparatus without requiring the user to disassemble and wash the apparatus.

Claims (6)

1. A kitchen exhaust apparatus including a volute housing in which is mounted a motordriven centrifugal fan, said volute housing having (a) a generally cylindrical portion surrounding the fan blades and having a base with an inlet port and (b) a generally tangential extension thereto formed with an upwardly-inclined sloping base and a gas outlet port above the slope, in which at least one first drain aperture is provided at or near the base of the slope, and at least one second drain aperture is disposed in the base of the cylindrical portion, generally at that starting point of the said base nearest the tangential extension in the sense of fan movement, a gathering plate being attached to the underside of the volute housing for joint collection of oleaginous and liquid components dropping down from said first and second drain apertures.

2. A kitchen exhaust apparatus as claimed in Claim 1 in which the second drain aperture is a slot.

3. A kitchen exhaust apparatus as claimed in Claim 1 or 2 in which the first drain apertures are constituted as a plurality of aligned slots across the lowest edge of the sloping base of the tangential extension.

4. A kitchen exhaust apparatus as claimed in Claim 1 or 2 in which the first drain apertures are constituted as a plurality of parallel slots each near, and at an angle to, the lowest edge of the sloping base of the tangential extension.

5. A kitchen exhaust apparatus as claimed in any one preceding claim, wherein the gathering plate is generally L-shaped and has an outlet in the base leading to a drain tube depending from the underside of the base at the rear for accommodation of a detachable container.

6. A kitchen exhaust apparatus as claimed in Claim 1 and substantially as herein described with reference to the accompanying drawings.