DK176977B1 - Step-adjustable pressure valve - Google Patents

Abstract

Apparatus for substantially silent supply of venation air from a duct system with overpressure to a point of consumption, comprising an air permeable, braking and muffler gasket (2) which is divided into sections in the direction of air flow by several separator plates (3). wherein the separating plates (3) are extended behind the gasket (2) as seen in the direction of the air flow and form several compartments (6), a desired number of which can be blinded and sealed for adjusting air flow but through the apparatus.

Description

DK 176977 B1 i

The present invention relates to an apparatus for substantially silent supply of ventilation air from an overpressure duct system to a consumption site, according to the preamble.

5 Devices of the above type are especially designed for a substantially silent supply of ventilation air from central ventilation units to the individual rooms or places of consumption in buildings with ventilation system of type CAV (Constant Air Volume) type 10 or VAV (Variable Air Volume).

In a CAV system, the air supply is constant but must be adjustable according to the experienced normal demand at the place of consumption. In a VAV system, the ventilation air flow rate is automatically varied as needed, usually 15 by room thermostat signal. Motion sensors are also widely used. The air supply appliance must therefore have capacity regulation.

In order to get the ventilation air to all places of consumption, a ventilation system of any size 20 must have a duct system with a certain overpressure on the air.

This applies not least to the VAV systems, which must be designed for maximum air consumption in the most remote consumption locations in the system. The air pressure in the ventilation ducts is preferably at 200-250 Pa in 25 large systems.

The problem with both the CAV and VAV systems is sound. If air is blown into a room from such pressure, an air velocity of 20 m / sec or more and a corresponding wind noise is obtained. If the airflow is set (CAV) or regulated (VAV) by means of a regulating damper which slows the air supply, corresponding or even higher noise occurs due to the turbulence of the damper. Such noise levels are at most DK 176977 B1 2 bothersome and completely unacceptable in modern ventilation systems.

A well-known method of reducing sound by air blow-in is to establish a pressure drop and a simultaneous sound attenuation by blowing air through a bundle of very thin, parallel tubes, diameter down to mm level, or through narrow gaps between a series of parallel plates, preferably of sound-absorbing material.

Other fillers are also conceivable. Narrow channels provide great resistance to air movement even at low speeds, resulting in a substantially silent braking of the air flow. The reason is that the flow picture through such narrow channels becomes essentially laminar. Several types of ap-15 air supply units blow in the air through such sound attenuating devices.

Adjustment or regulation of the air flow through such an air inlet device must be effected by dimming a larger or smaller portion of the flow cross-section of the insert or gasket provided for virtually silent braking of the airflow. If the front pressure is constant - approximately as it will be in CAV and VAV systems, the air supply will vary proportionally to the open, unblended cross section of the gasket. On the other hand, a single control damper in the duct in front of the apparatus will not function satisfactorily for sound, as the air noise due to the turbulence in the damper will not be sufficiently attenuated through the gasket.

Embodiments of blower apparatus based on virtually silent braking of the airflow through gaskets as described above are described in NO 99 202. The patent discloses such an apparatus in which DK 176977 B1 3 capacity control is achieved by a disc (planar embodiment) or a cylinder (cylindrical). embodiment) which is close to the surface of the gasket, is slid or rotated back and forth thereby covering a greater or smaller portion of the gasket flow area. This results in an infinite capacity adjustment or an infinite capacity adjustment from 0 to 100%, which is adapted to a desired continuous control curve.

10 A completely infinite adjustment of the ventilation airflow to each room or consumable place in a CAV system or infinitely continuous control of the airflow in a VAV system is expensive and in most cases not necessary.

A CAV ventilation blower according to the present invention will provide a substantially silent supply of ventilation air, and can be simply adjusted for multiple capacity air flow in a simple and inexpensive manner, 20 without the use of slidable plates. or dampers or other moving parts as defined by the features specified in the claims.

A VAV ventilation blower according to the present invention will also provide a substantially silent supply of capacity ventilation air, which is automatically controlled in two or three stages and the airflow in each stage can be adjusted in several minor steps in a single step. simple and inexpensive manner, as defined by the features set forth in the claims.

In the drawing, Fig. 1 is a schematic sectional view of a CAV valve according to the present invention; 2 is a sectional view of a two-stage VAV valve.

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DK 176977 B1 4 yellowing according to the present invention, fig. 3 is a three-stage VAV valve in accordance with the present invention; and FIG. 4 is a perspective view of an example of a gasket type for substantially silent braking of the airflow which can be used in apparatus according to the invention.

In the preferred embodiments of the invention, the portion of the apparatus containing the gasket 10 has a rectangular cross section. Other cross-sectional forms, e.g. circular cross section, is conceivable but not so convenient for adjusting capabilities according to the invention. All types of gaskets are conceivable as long as they are permeable to air with a substantially silent braking of the airflow.

FIG. 1 shows a CAV apparatus for constant but in step adjustable airflow according to the invention. The appliance is connected to a common duct for supplying ventilation air. The arrows indicate the flow direction of the air. Inside the outer casing 1 of the apparatus a gasket, of the type shown in FIG. 4 or another type which provides a substantially silent braking of the air flow. The gasket is divided by several airtight separating plates 3, which provide a similar number of separate airflows through the gasket. The separating plates 3 are extended backwards on the outlet side of the apparatus, so that a corresponding number of open outlet spaces 4 are formed for the air coming out of the gasket. An apparatus according to the invention 30 is provided with a necessary number of flexible and adapted strips which can be pressed into the outlet compartments, each blinding its outlet compartment as shown. Thus, the airflow in question is effectively shut off and the airflow through it is reduced accordingly. This is the case when the air pressure in the common duct is constant, something it approximates to a CAV system. The outlet side of the apparatus is open and easily accessible from the outside, which makes it easy to make step-by-step adjustment and re-adjustment of the air volume as required by inserting or removing strips 5.

FIG. 2 shows in section an adjustable VAV apparatus according to the invention with two control steps. Within the outer sheath 1, the gasket 2 is divided into several separate parts, in the preferred embodiment of the invention ten parts, by means of intermediate sealed plates 3.

One of the plates is extended forward so that the apparatus in front of the gasket is divided into two separate inlet compartments 6 and 7. The inlet to one compartment 6 can be closed with a tight, motor controlled damper 8. In the preferred embodiment of this apparatus the compartment covers 6 approx.

30% of the total flow area, and the space 7 approx. 70%. The damper 8 has just two positions: fully 20 open or fully closed. With fully open damper the appliance has 100% air capacity and with a closed damper approx. 70%. As with the CAV apparatus, the sheath 1 and the sheet plates 3 are extended slightly beyond the gasket on the outlet side of the apparatus, so that the outlet space is divided into a corresponding number of compartments 4. From the readily accessible outlet side of the apparatus, easily adapted and flexible strips 5 can be pressed in easily. which blinds one or more of the compartments 4 thereby reducing the air flow area accordingly. If, for example, one of the compartments 4 behind the part of the gasket that gets air through the compartment 7 is blinded in this way, the apparatus will have capacities of 90% and 60% with open and closed dampers, respectively 8. The airflow in DK Both control steps can be easily changed from the outlet side of the apparatus in this way.

FIG. 1 shows in section a corresponding VAV apparatus as in FIG. 2, but with three separate inlets and two 5 dampers for three control steps. In the preferred embodiment of the invention, this apparatus also has 9 dividing plates dividing the gasket into 10 separate races, and each of the damper closable spaces in front of the gasket covers 30% of the through-section. This provides re-10 leveling steps for 100%, 70% and 40% capacity when no, one or both dampers are closed, respectively. This apparatus also, in the same way as the apparatus with two control stages, has extended separating plates backwards on the outlet side where they form spaces 15 which can be blinded by strips, which can thereby reduce and adjust the capacity as required in all the control steps.

FIG. 4 shows in perspective and enlarged section an example of a type of gasket which can be used in apparatus according to the invention and which provides a substantially silent braking of the air flow as described above.

Claims (6)

An apparatus for substantially silent supply of ventilation air from an overpressure duct system to a point of consumption, comprising a permeable, slowing and sound-absorbing gasket (2) divided by sections (3) into sections in the direction of air flow, characterized in that the separating plates (3) are extended behind the gasket (2) in the direction of the air flow and form 10 more compartments (4), a desired number of which can be blinded and sealed to adjust the air flow through the apparatus. Apparatus according to claim 1, characterized in that the compartments (4) can be blinded and sealed with flexible strips (5). Apparatus according to claim 1, characterized in that at least one separating plate (3) is extended forward towards the direction of the air flow, so that the cross-section of the apparatus in front of the gasket (2) is divided into at least two separate spaces (6) which can is closed and opened individually with a damper (8) for regulating the air flow through the apparatus. Apparatus according to claim 3, characterized in that each damper (8) can be operated automatically with a damper motor. Apparatus according to claim 3, characterized in that each damper (8) can be operated manually with handles on the outside of the apparatus. Apparatus according to one of the preceding claims, characterized in that the gasket (2) consists of plastic or corrugated cardboard with a large number of narrow and separated ducts in the direction of the air flow.