VALVE FOR CONTROLLING THE VENTILATION FLOW FROM A KITCHEN RANGE HOOD

Abstract: The present invention relates to a valve for controlling the flow of ventilation air from a kitchen range hood, and comprises means (8) for allowing a basic flow of ventila­ tion air to pass through the valve, when in its closed position. According to the invention, the valve has an opening (8, 9), the area of which is adjustable.

Description: The present invention relates to a valve for controlling the ventilation flow from a kitchen range hood according to the preamble of claim 1. Such a valve is known by our Swedish patent No. 443 643, which comprises a through opening, through which a basic flow of ventilation air passes in the closed position of the valve. The size of this opening can be adjusted at the installation of the valve in the exhaust air outlet of the range hood by cutting off a portion of a conically tapered tube. The present invention intends to improve such a valve by making it so that the size of the basic flow of ventilation air can be adjusted more accurately and even be readjusted later. In order to achieve this, a valve of the type described by way of introduction is characterized according to the invention in that the valve has means for varying the area of the opening in the closing means. The area of the opening can thereby be set very accurately depending on the measured values of the pressure drop over the valve in the closed position. Furthermore, it is possible to readjust the area of the opening later if this should prove necessary, for example due to altered flow conditions in the exhaust duct. A preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows in perspective a valve according to a preferred embodiment of the invention, Figure 2 shows a plan view of a valve cover included in the valve shown in Figure 1, Figure 3 shows a plan view of a constriction disk in the valve according to Figure 1, and Figures 4 and 5 show a plan view and an axial section throguh a pipe stub supporting the valve cover and the constriction disk. The valve shown in Figure 1 has three main components, namely a valve cover 1, a constriction disk 2 and a pipe stub 3, which supports the valve cover 1 and the constriction disk 2. The valve cover 1 is hinged at 4 to an end flange 5 of the pipe stub 3. Furthermore, the valve cover is dimensioned so that it covers in the closed position of the valve the opening of the pipe stub 3 since the outer peripheral portion will be in contact with an inner portion of the ring surface of the end flange 5. The constriction disk 2 is also fixed in a suitable manner to the flanged end of the pipe stub 3. The entire valve is fixed in a suitable manner in a range hood (not shown) with the non-flanged end of the pipe stub 3 connected to the evacuation duct of a central ventilation system. In the opened positioned of the valve shown in Figure 1, air is evacuated from the interior of the range hood through the constriction disk 2 and the pipe stub 3 to the evacuation duct. The size of the flow through the constriction disk can be adjusted by changing the size of the opening therein. For this purpose, as is best shown in Figure 3, the constriction disk 2 is provided with, in addition to a minimum opening 6, rupture indications 7 to facilitate the making of a larger opening in the constriction disk. As can be seen in Figures 1 and 2, the valve cover 1 also has an opening 8 which, as can best be seen in Figure 1, is made in a portion of the valve cover projecting towards the pipe stub. In the closed position of the valve, this projecting portion of the valve cover 1 extends through the opening 6 of the constriction disk 2. Even when the valve is closed, air will flow from the interior of the range hood through the opening in the valve cover to the evacuation duct. In order to make it possible to adjust the size of this basic flow of ventilation air, a sliding shutter 9 is slideably mounted in the valve cover 1 with the aid of guides 10. The sliding shutter 9 makes it possible to cover the opening 8 to the desired degree. A scale 11, as shown in Figure 2, can preferably be arranged beside the opening 8 to determine the position of the sliding shutter 9 relative to the opening. A metering outlet 12 is arranged in the pipe stub 3 to make it possible to measure the pressure drop over the valve. The metering outlet 12 consists of a tube opened at both ends, which extends from a position upstream of the flange 5 through the flange peripherially outside the valve cover in its closed position and through the wall of the pipe stub 3 opening into the interior of the pipe stub downstream of the constriction disk 2. By integrating the metering outlet with the pipe stub and making it easily accessible through its end projecting from the flange 5, to which a measuring instrument can easily be connected, the pressure drop over the valve can be measured with the valve mounted in place without intervention on the pipe stub or the evacuation duct regardless of whether the valve is opened or closed. The installation and adjustment of a range hood with such a valve is thus facilitated significantly over previously known designs. The size of the openings 6 and 8 in the open and closed positions of the valve can thus be selected and adjusted depending on the measured pressure drop. By making the valve cover with an opening with an adjustable cross sectional area, a very accurate adjustment of the basic flow of ventilation air can be made. Furthermore, the position of the sliding shutter 9 can be changed if changed flow conditions should arise for any reason in the central ventilation system. In the example shown, the sliding shutter 9 is easily accessible, when the valve is in its closed position, for adjustment from the non-flanged end of the pipe stub 3, if the pipe stub is removed from the evacuation duct. Preferably, however, the sliding shutter is also accessible from the underside of the range hood when the range hood filter unit is removed. The position of the sliding shutter can thereby be changed without completely or partially removing the valve. The valve cover 1 also comprises a bow 14, coupled to an actuating mechanism (not shown) disposed in the range hood for swinging the valve cover between a closed and an open position. The valve according to the invention thus provides a simple and exact method of adjusting and/or readjusting the basic flow of ventilation air in a range hood. Furthermore, the range hood can, in one variation, be provided with a mechanism, by means of which the sliding shutter, in the closed position of the valve, can be adjusted from outside the range hood. It is also possible to make the valve cover and the sliding shutter with interaction projections and cavities for indicating various displacement positions for the sliding shutter relative to the valve cover, and a clamping mechanism can be arranged to keep the sliding shutter in the said position.

Claims: Valve for controlling the ventilation flow from a kitchen range hood, comprising an evacuation opening (6) in a duct (3) leading to the evacuation duct for the kitchen range hood and closing means (1) for closing the duct (3) containing the evacuation opening (6), the closing means (1) being moveable between a closed position, in which the duct (3) containing the evacuation opening (6) is closed, and an open position, in which said duct (3) is fully opened, the closing means (1) further comprising an opening (8) for permitting a basic flow of ventilation air to pass through the valve in the closed position of the closing means, characterized by means (9) for varying the area of the opening (8) in the closing means (1). Valve according to Claim 1, characterized in that a sliding shutter (9), which is slideably displaceable on a valve cover (1), more or less covers the through opening (8) in the valve cover depending on its displacement position. Valve according to one of Claims 1 and 2, characterized in that the valve cover (1) is hinged to the end (5) of a pipe stub (3) and that the valve cover (1), in the closed position of the valve, covers the end opening of the pipe stub (3). Valve according to one of Claims 2 or 3, characterized in that a constriction disk (2) is arranged in the pipe stub (3) in the same end portion which cooperates with the valve cover (1), said constriction disk having a constriction opening (6). Valve according to Claim 4, characterized in that the valve cover (1) on the side facing the pipe stub (3) comprises a projection portion which contains the opening (8) and which extends, in the closed position of the valve, through the opening (6) in the constriction disc (2). Valve according to one of Claims 1-5, characterized in that a metering outlet (12) is arranged in the pipe stub (3) to permit measurement of the pressure drop over the valve.

Inventors: HEDMAN, PER-MARTIN, LUNDQVIST, GOESTA, WALLIN, SVEN-OLOV, Lundqvist, Gösta
Applicants: FUTURUM AB
Application year: 1989
Main classification: F24C15
IPC codes: F24C15