Kitchen ventilator

Abstract: A kitchen ventilator, comprises a collecting box (11) supporting on its upper side a fan casing (10) enclosing a chamber which, by means of an essentially vertical partition (21), delimits an inlet channel (23) and a fan housing with an outlet channel (18), respectively, said collecting box (11), via an outlet opening (19) provided in its upper wall, being connected to the inlet channel (23) and the fan housing contains a fan (16) rotatable in a vertical plane, the inlet side of which being connected to the inlet channel (23) via an essentially circular opening (20) provided in the partition (21) and the outlet side of which being connected to the outlet channel (18), said inlet and outlet channels (23,18) being formed by inserts (22,17) made of sound-absorbing material. The outlet opening (19) in the collecting box (11) is displaced laterally relative to the opening (20) in the partition (21) and the inlet channel (23) has a curved shape adapted to the direction of rotation of the fan (16) so that the incoming flow is deflected in said direction of rotation.

Description: The present invention relates to a kitchen ventilator comprising a collecting box supporting on its upper side a fan casing enclosing a chamber which, by means of a mainly vertical partition, delimits an inlet channel and a fan housing with an outlet channel, respectively, said collecting box, via an outlet opening provided in its upper wall, being connected to the inlet channel and the fan housing contains a fan rotatable in a vertical plane, the inlet side of which being connected to the inlet channel via an essentially circular opening provided in the partition and the outlet side of which being connected to the outlet channel, said inlet and outlet channels being formed by inserts made of sound-absorbing material. Devices of the kind indicated above are provided for the purpose of removing fumes, vapors and the like emitted during cooking from frying pans and kettles on top of a range or from an oven included in the range. Most often, such a ventilator is disposed above the cooking surface of the range at a height above the surface permitting the convenient handling of the pans and kettles or the like placed on the cooking surface without reducing, to an annoying extent, the ability of the kitchen ventilator to collect the fumes, vapors and the like. Often, kitchen ventilators for domestic use have a relatively non-complex build-up comprising a fan driven by an electric motor housed in a fan housing provided with an inlet channel and an outlet channel. Often, the fan housing is disposed on top of a flat box-shaped collecting chamber which extends above the cooking surface for the purpose of collecting fumes, vapors and the like from the space adjacent to the cooking surface. The inlet channel is connected to the collecting chamber to convey the fumes, vapors and the like to the inlet of the fan to be forwarded to an outlet which can open to the surrounding room (charcoal filter fan) or into a ventilation duct leading into the open air. A common problem associated with kitchen vantilators is to combine the two contradictory desires of achieving a good suction power and a low noise level. In case a good suction power is to be achieved, most often, the result will be that the noise from the fan and the flowing air reaches annoyingly high levels. Therefore, in more expensive models of kitchen ventilators sound absorbing material has been provided in order to reduce the noise level. An example of a kitchen ventilator of this kind is given in EP-B1-0149053. Part of the prior art is also EP-A1-0596846 which discloses a kitchen ventilator wherein a fan is disposed in a housing connected to an outlet. The inlet to the fan has the shape of a circular opening in a partition which separates the fan housing from an inlet channel conveying fumes, vapors and the like from the surrounding space via a collecting box and to the opening in the partition. The object of the invention is to offer an effective way of handling the noise problems associated with kitchen ventilators without causing the construction of the ventilators to become more complicated and hence more expensive. The object is achieved in a device of the kind indicated in the preamble of claim 1 in which the features of the characterizing part of the claim have been included. Preferred embodiments have been included in the accompanying sub-claims. The invention will now be described more in detail in connection with an embodiment with reference to the enclosed drawings, in which: Fig. 1 is a schematic perspective view of a device according to the invention; Fig. 2 is an exploded view of the device of Fig. 1; Fig. 3 is a front view showing the sound absorbing insert, which forms the inlet channel, and the partition behind, and Fig. 4 is a side view of the sound absorbing insert of Fig. 3. Fig. 1 shows a kitchen ventilator of a conventional exterior design with a fan casing 10 disposed on top of a collecting box 11. The kitchen ventilator can be mounted separately on a wall above a range or it can be combined with a spice-rack or the like secured to the wall. The collecting box 11 encloses a collecting channel 12 provided to collect fumes, vapors and the like sucked into the collecting box via suitable channels, e.g. a larger opening covered by a filter for separating fat. Any detailed description of the collecting box with inlet openings, filter and the like will not be given. On top of the fan casing 10 an outlet opening 13 is provided through which air is discharged either to the surrounding space after having passed a char-coal filter, not shown, or to a ventilation duct leading into the open air. As better shown in Fig. 2, the fan casing 10 comprises a front portion 14 and a rear portion 15. The portions 14, 15 are joined by means of screws or the like. In the rear fan casing portion 15 there is provided an impeller 16 which is rotated by an electric motor, not shown. In the fan casing portion 15, which has the shape of a rectangular box, an insert 17 is provided which is formed of sound absorbing material. The insert forms a spiral outlet channel 18 which extends around the impeller 16 and opens into the outlet opening 13. The front fan casing portion 14 forms an inlet housing the object of which is to convey the fumes, vapors and the like from an outlet opening 19 of the collecting box 11 to an inlet opening 20 to the fan. The inlet housing is displaced laterally with respect to an axial plane of symmetry 27 through the fan extending perpendicularly to a plane surface 11a supporting the fan casing 10. The inlet opening 20 is provided in a partition 21 separating the two fan casing portions 14 and 15 and situated just in front of the impeller 16 which is of the radial fan type, i.e. air is sucked-in axially and blown-out radially. The fan casing portion 14 has an insert 22 of sound absorbing material forming a curved inlet channel 23. The curved shape of the inlet channel 23 between the outlet opening 19 in the collecting box 11 and the opening 20 in the partition 21 leading to the fan is adapted to the direction of rotation of the impeller 16 so that the inlet air flow is deflected in the direction of rotation. As a result, already before reaching the impeller 16 the flow will obtain a rotating motion facilitating the continued flow movement through the fan, via the outlet channel 18 and to the outlet opening 13. In this way the efficiency of the fan will increase. The sound absorbing material can consist of e.g. glass-wool or polyurethan. Due to the fact that the inserts 17 and 22 forming the inlet and outlet channels, will be exposed to air which is both humid and not completely freed from fat, suitably, a protecting layer which is moisture repellant and fat proof is applied to the surfaces forming said channels. One example of such protecting layer is a thin film of polyurethan suitably applied by spraying onto those parts of the inserts forming the channels. Now, reference is made to Figs. 3-4 showing more specifically the design of the inlet channel 23. In Fig. 3, which shows the insert 22 and the partition 21 behind, it appears that the inlet channel bends from left to right. The opening 20 in the partition 21 is displaced to the right with respect to a vertical line of symmetry 25. The task here is to give to the inlet channel a shape that permits a flow as large as possible without the noise level becoming annoyingly high. In order to increase the flow of air and fumes it has been found to be advantageous, in addition to the direct air flow directed to the opening 20 to convey air to the opening also from the opposite side, i.e. from above in the drawing. To this end the inlet channel 23 extends in a curve to the left of the opening 22 following essentially a parabolic curve to a point A situated at the edge of the opening at about 2 o'clock, if for a moment the opening is looked upon as a clock. The highest point B of the parabolic curve is situated essentially at the point where the parabolic curve intersects the line of symmetry 25. In addition, this point is situated at a distance above the upper edge of the opening 20 (in the direction of the line of symmetry 25) which is about a quarter of the diameter of the opening 20. The opposite, right-hand side of the inlet channel follows the curvature of the opening to a point C at about 5 o'clock and continues from there towards the right-hand side of the outlet opening 19 in a smooth curve directed towards the channel. Adjacent to the outlet opening 19 the two channel walls on opposite sides of the opening deflect towards one another for the smooth guidance of the air from the opening and into the inlet channel 23. The right-hand edge of the outlet opening 21 from the collecting box 11 coincides essentially with the point of intersection of the line of symmetry 25 and the plane surface 11a. The described shape of the inlet channel 23 contributes in counteracting tendencies of turbulence with the associated reduction of the flow. Such turbulence is further conteracted by giving the insert 22 a design as shown in Fig. 4. Due to the fact that, as seen from the side, the insert 22 and hence the inlet channel 23 narrows in an upward direction to obtain a funnel-like shape, incoming air and fumes are led from the outlet opening 19 to the inlet opening 20 to the fan 16 in a way which is advantageous from an aerodynamic point of view. In addition, by the openings 19 and 20 being displaced laterally with respect to one another direct transmission of undesired fan noise to the inlet side of the kitchen ventilator is hampered and the noise is damped by the sound absorbing material forming the side walls of the inlet channel. When the fan is put into operation the impeller 16 rotates in the direction indicated by an arrow and air is sucked into the collecting box 11 and further through the outlet opening 19 from the collecting box 11 and into the inlet channel 23. Due to the curved shape of the channel and the lateral displacement of the outlet opening 19 the incoming flow is given a rotating motion in the direction of rotation of the impeller 16 and exits via the opening 20 in the partition 21 as a rotating flow which is caught by the impeller 16 to be conveyed into the spiral outlet channel 18 from which the flow exits via the outlet opening 13. Due to the shape of the insert 22 causing it to completely fill the space between the front fan casing portion 14 and the partition 21 the greatest possible utilization of the sound absorbing material is obtained and hence a most efficient damping of the undesired noise. At the same time there is avoided the usually inevitable increase of the degree of complexity of a soundproof kitchen ventilator as compared to a conventional one which is not soundproof. This also means that the positive results with regard to the efficiency and low noise level of the ventilator are obtained without any significant increase in cost associated with the manufacture of such kitchen ventilator.

Claims: Kitchen ventilator, comprising a collecting box (11) supporting on its upper side a fan casing (10) enclosing a chamber which, by means of an essentially vertical partition (21), delimits an inlet channel (23) and a fan housing with an outlet channel (18), respectively, said collecting box (11), via an outlet opening (19) provided in its upper wall (11a), being connected to the inlet channel (23) and the fan housing contains a fan (16) rotatable in a vertical plane, the inlet side of which being connected to the inlet channel (23) via an essentially circular opening (20) provided in the partition (21) and the outlet side of which being connected to the outlet channel (18), said inlet and outlet channels (23,18) being formed by inserts (22,17) made of sound-absorbing material, characterized in that the outlet opening (19) in the collecting box (11) is displaced laterally relative to the opening (20) in the partition (21) and that the inlet channel (23) has a curved shape adapted to the direction of rotation of the fan (16) so that the incoming flow is deflected in said direction of rotation. Kitchen ventilator according to claim 1, characterized in that the inlet channel (23) has a shape such that at the side of the opening (20) in the partition (21) where air arrives in the direction of rotation of the fan (16) the channel (23) extends laterally outside of the opening (20), whereas at the opposite side of the opening (20) the channel wall essentially conforms to the opening (20). Kitchen ventilator according to claim 2, characterized in that the front wall (14) of the fan casing (10), which delimits the inlet channel (23), slopes from an upper narrow portion, as seen from the side, to a broader portion at the bottom, said wall with a smooth curvature connecting to the outlet opening (19) provided in the collecting box (11) and leading to the inlet channel (23). Kitchen ventilator according to claim 3, characterized in that , laterally, the walls of the inlet channel (23) have a shape such that they deflect towards one another adjacent to the outlet opening (19) in the collecting box (11). Kitchen ventilator according to claim 4, characterized in that at the side where the inlet channel (23) extends outside of the opening (20) in the partition (21) the channel wall essentially follows a parabolic curve the highest point of which (B) being situated at a distance above the upper edge of the opening (20) in the partition (21) amounting to about a quarter of the diameter of said opening and, further, being positioned on a vertical line (25) nearly connecting to the right-hand side of the channel wall at the outlet opening (19) from the collecting box (11), said channel wall from the parabolic curve shifts to essentially follow the right-hand edge of the opening (20) in the partition (21).

Inventors: STRAND MARKUS, STRAND, MARKUS
Applicants: ELECTROLUX ABP, AKTIEBOLAGET ELECTROLUX (PUBL.)
Application year: 1997
Main classification: F24C15
IPC codes: F04D29, F24C15