Patent Publication Number: US-6218654-B1

Title: Flow control device for a ventilator hood

Description:
TECHNICAL FIELD 
     The present invention relates to a domestic appliance comprising an oven and a ventilator device in a common casing according to the preamble of the appended claim  1  and a flow control means and the use thereof in such an appliance. 
     PRIOR ART 
     Domestic appliances which in a common unit comprise a microwave oven and a ventilator hood are previously known. Such combinations of a ventilator hood and a microwave oven are intended to be installed over a range and offer efficient utilisation of the space above a range. 
     Usually, the ventilating duct in such domestic appliances has an outlet which at the time of installation is adjustable to suit various designs and placements of subsequent kitchen flues in a building. Often, as an alternative, the outlet of the ventilating duct can guide the flow in the duct to recirculation, e.g. when the building lacks a suitable kitchen flue, so that the ventilator hood can function as a recirculation ventilator, together with a suitable filter. 
     These known domestic appliances have a ventilator unit arranged directly opposite an outlet opening. Usually, the outlet opening is formed as a rectangular opening in the transition area between the top and back of the appliance. In this connection, the ventilator unit is formed as a radial ventilator with twin rotors, which are arranged on each side of a centrally located electric motor. The ventilator has a horizontal rotation axis extending in the transverse direction of the appliance. The diameter of the rotors essentially corresponds to the dimension of the outlet opening in the direction upwards-downwards or forwards-backwards. The ventilator unit forms a rectangular parallelepiped and can be placed in different turning positions around its rotation axis for adjustability between outlet upwards or backwards to a ventilating duct in the building or for outlet forward through a second outlet opening on the front of the appliance for recirculation. 
     One problem associated with this known construction is that the ventilator and the air currents give rise to high sound levels. 
     Furthermore, there are special problems associated with ventilator devices which are combined with an oven, such as combining a number of appliance components and ventilating ducts in a limited volume in a common casing. Therefore, there are problems of low ventilator efficiency because of uncontrolled flow in the appliance. In known appliances, a high percentage of the air which is blown out through the ventilator leaks into the outer casing of the appliance from a different location than the intended inlet opening. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to achieve an improved ventilator device in a domestic appliance comprising an oven and a ventilator device in a common casing. 
     In this connection, special objects are to lower the sound level of the ventilator device and to achieve improved controllability of air currents in the appliance. 
     These and other objects, which can be seen from the description below, have now been achieved by the invention by means of a domestic appliance and a flow control means, which are of the kind described in the introduction and which in addition have the features stated in the characterising clauses of claims  1  and  9 , and by a use of the flow control means according to claim  16 . 
     Thus, in the domestic appliance according to the invention, the ventilator is stationarily mounted on the inside of the casing, spaced from an outlet opening. 
     In addition, the ventilating duct has a flow control means arranged downstream of the ventilator on the inside of the casing for adjusting the ventilating duct to lead to any one of at least two different outlet locations. 
     In this way, it becomes possible to choose the location and the design of the ventilator inside the casing or cover of the appliance. For example, the ventilator can be given a larger radius or be located closer to the intake opening of the appliance. Greater possibilities are afforded for the design of a suitable ventilating duct in coaction between the ventilator and the other components of the appliance. In addition, it becomes possible to utilise a larger part of the area of the outlet opening for the outlet air, which means that an equally large volume flow rate can be ventilated at lower outlet velocities. This, in turn, leads to lower sound levels than have been possible in known appliances, in which ventilator constructions only allow a smaller part of the outlet opening to be utilised. 
     In a preferred embodiment the flow control means is adapted to change the direction of a flow in the ventilating duct. As a result, the adjustability of the flow control means and the optional location of the ventilator can be achieved in a simple way by the fact that the flow control means can be placed in various turning positions around an intake from the ventilator. 
     In a particularly preferred embodiment, the flow control means has a control means housing with a smaller inlet and a larger outlet in order to function as a diffuser. In this way, the velocity of flow in the outlet can be lowered, which leads to lower sound levels. At the same time, the ventilating duct can be given a limited cross-sectional area between the ventilator and the flow control means. 
     It is a preferred feature that the ventilator be given a relatively large radius, larger than the smallest dimension of the outlet opening, something which has been the case in the known solutions. By virtue of a larger radius, the peripheral speed of the ventilator can be reduced in relation to the flow rate, which leads to lower rotation speeds and thus lower sound levels. It is a particularly preferred feature that the ventilator be arranged in the form of a radial ventilator which rotates around an asymmetrically located, vertical rotation axis in an upper area of the appliance. In this way, the radius of the ventilator will only be limited by the horizontal cross-sectional dimensions of the appliance. 
     A flow control means according to the invention has an elongated control means housing and comprises an outlet opening, which is arranged along a long side, and an inlet opening, which is arranged along another side. The inlet opening has a smaller opening area than the outlet opening. In addition, a deflecting device is arranged to deflect and distribute the flow essentially uniformly at the outlet. 
     Such a flow control means has proved to be extremely suitable for controlling a flow to an outlet opening in a domestic appliance with a ventilator in combination with an oven. The flow control means according to the invention also affords great advantages in appliances which have a fixed outlet location. 
     In a preferred embodiment, the deflecting device comprises a plurality of deflecting means, which are essentially uniformly arranged along a projection of the inlet opening perpendicular to its essential geometrical plane and at the same time essentially uniformly arranged along a projection of the outlet opening perpendicular to its essential geometrical plane. In this way, deflection of the air current as well as a reduction of velocity and a uniform distribution of the same over the larger area of the outlet are achieved with a small loss of energy. 
     The deflecting means of the flow control means preferably comprises deflecting blades which are somewhat curved and have a leading edge facing the inlet opening and a trailing edge facing the outlet opening. In order to achieve good flow characteristics and little energy loss, it is particularly preferred that the leading edge of the blades be rounded and that the trailing edge be pointed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in more detail below with reference to the accompanying drawings, which show presently preferred embodiments of the invention. 
     FIG. 1 shows a domestic appliance according to the invention in a perspective view obliquely from the front from above. 
     FIG. 2 shows the domestic appliance according to FIG. 1 in a perspective view obliquely from behind from below. 
     FIG. 3 shows the domestic appliance according to FIG. 1 with certain parts removed in order to illustrate the function of the appliance. 
     FIG. 4 is a schematic longitudinal section along the line IV—IV in FIG. 3 for illustrating the flow of air through the appliance. 
     FIG. 5 is a schematic cross-section along the line V—V in FIG. 3 for illustrating the flow of air out from the appliance. 
     FIG. 6 is a perspective view of a flow control means according to the invention. 
     FIG. 7 shows the flow control means in FIG. 6 in a disassembled state. 
    
    
     DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS OF THE INVENTION 
     FIGS. 1 and 2 show a domestic appliance  10  which in one unit is a combination of a microwave oven and a ventilator hood (Over-the-range) to be located above a range. The appliance  10  comprises a casing  50  which has the form of a rectangular parallelepiped. On the front  53  of the casing  50  there is a door  61  for the microwave oven  60  and a control panel  62 . On the underside  51  of the casing  50  there is an inlet opening  23  with a grate for the ventilator hood and on the back  54  and the top side  52  there is an outlet opening  24  extending along the intermediate edge  55 , which opening is intended to be connected to a building kitchen flue located above or behind it, adjacent to an upper or a rear outlet location  24   a  or  24   b  respectively. In the embodiment shown, the shape of the outlet opening is specially adapted to a kitchen flue with a rectangular cross-section. On the front  53 , there is also a second outlet opening  25 , which is provided with a grate and intended for recirculation of air if the ventilator hood is used as a recirculating ventilator, e.g. when the building lacks suitable ventilating ducts. A ventilating duct extends in the casing  50  between the inlet opening  23  and the outlet openings  24  and  25 . It can be seen from FIG. 5 that the air current is adjustable between three different outlet locations  24   b,    24   a,    25 , each of which corresponds to a respective outlet route  16 ,  17 ,  18  for adjustment to the existence and location of kitchen flues in the building. The features described so far correspond to the features of a conventional type device. 
     In FIG. 3, the appliance  10  is shown with certain parts cut away, which makes it possible to see an adjustable flow control means  30 , which will be described in more detail below, and a radial ventilator  22 , which is spaced from the outlet opening  24 . Around the ventilator  22 , there is a ventilator casing duct  26  which collects and guides the air current on the driving side of the ventilator to the flow control means  30 . These parts form part of the ventilating duct  21  of the appliance  10 . The flow control means  30 , which is elongated is, e.g. in connection with the installation of the appliance, adjustable in the turning position around its longitudinal axis for adjustment of the outlet location and outlet route of the ventilating duct  21  according to FIG.  5 . 
     The ventilator  22 , the ventilator casing duct  26 , the flow control means  30  and a recirculation duct  27 , which extends between the flow control means  30  and the recirculation outlet  25 , are all arranged in an upper plane  57  directly below the top side  52  of the casing  50 . As can be most clearly seen in FIG. 4, this upper plane  57  is arranged above and spaced from the oven  60  in order to permit the supply of air between them. The ventilating duct  21  consists of the free volume in the casing  10  which is not taken up by the oven  60  and by drive components  63  for the oven and the ventilator. As can be seen in FIG. 4, the ventilating duct  21  with two sub-ducts  21   a  and  21   b  extends from the inlet opening  23  on one side around the oven  60  and on the other side around the drive components  63  of the appliance. 
     The location and design of the ventilator  22  shown in FIG. 3 offers many advantages. For example, it has been possible to give the ventilator  22  a large diameter, here in the range of ⅓ to ½ of the depth of the top side  52 . Further, the asymmetric location of the ventilator  22  allows the motor to be located in the space beside the oven  60 . The location of the ventilator  22  relatively close to the outlet opening permits the achievement of an even, directed flow in the ventilator casing duct  26  while the ventilating duct  21  can be made short on the driving side, i.e. the part which has to be particularly carefully sealed. 
     In addition, the risk of leakage of currents into the casing adjacent to the outlet opening  24 , which has been a problem in known constructions, is reduced by the ventilator and in particular its intake being located spaced from it. 
     The embodiment shown with an elongated flow control means  30  in the outlet opening  24  is very well suited to be connected to kitchen flues with a rectangular cross-section. A major advantage in this connection is that a perpendicular and uniformly distributed flow is achieved over the whole area of the outlet opening, which leads to a small loss of energy and low sound levels. 
     The flow control means  30  according to the invention is described in more detail below with reference to FIGS. 6 and 7. The ventilation control means  30  has two simultaneous functions, one being to function as a diffuser, and the other being to change the direction of the flow. By the ventilation control means  30  according to the invention, both these tasks are accomplished while, at the same time, a uniform flow is maintained along the outlet area of the ventilation control means  30 . 
     The ventilation control means  30  has a control means housing  39  which is shaped like a rectangular parallelepiped with an inlet opening  31 , which consists of a square short side. Furthermore, there is an outlet opening  32 , which consists of a whole long side. The flow into and out of the flow control means  30  is indicated by flow arrows  36 ,  37 . A deflecting device  40  comprising deflecting means in the form of deflecting blades  47  for deflecting the flow uniformly along a line extending diagonally in relation to the inlet as well as the outlet direction  36  and  37 , respectively, extends in the ventilation control means  30 . 
     FIG. 7 shows the flow control means  30  in a disassembled state, which means consists of an elongated cover  35  with a U-shaped cross-section and open short ends, as well as a deflecting unit  45 , which in one piece incorporates deflecting blades  47 , a holder device  43  for the deflecting blades  47  and a short side wall  46 . The housing  39  of the control means is formed by the cover  35  and the short side wall  46 . 
     The cover  35  is preferably made of plastic and has holder openings  34  for coaction with corresponding holder pins  44  on the deflecting unit  45  in the assembled state. Guide bars  38  are arranged on the inside of the cover  35  along the central long side  33  to guide the surface flow. 
     The deflecting unit  45 , too, is preferably integrally formed in plastic and has a set of deflecting blades  47  uniformly located along a straight line. The holder device  43  consists of an essentially triangular flat plate extending perpendicular to the deflecting blades  47 , parallel to the direction of flow. The holder device  43  is connected to the short side wall  46 , perpendicular to the same. 
     The blades  47  are elongated transversely of and bent along the direction of flow and have a leading edge  41 , which is rounded and when assembled faces the inlet opening  31 , and a trailing edge  42 , which is pointed and when assembled faces the outlet opening  32 . 
     The holder pins  44  are formed on the ends of the blades  47  and on the short-side wall  46 . 
     On the end which is turned away from the outlet opening  32 , the short-side wall has a bent portion  48  for the smooth deflection of the flow along the inside surface of the flow control means  30 . 
     The dividing of the flow control means into a cover and a deflecting unit allows for expedient and efficient manufacturing and assembly.